dsprpcd: Add help functionality

[quic-vkatoch]

Add -h/--help support to display daemon usage, functionality, DSP-specific shell file naming conventions, and command-line options with appropriate examples for each DSP subsystem.

root@qcs9100-ride-sx:/usr/bin# ./adsprpcd -h
Usage: ./adsprpcd [OPTION]...
Daemon that establishes a connection to ADSP.
If audiopd is passed as an argument to this daemon, it will connect to audio PD on ADSP.
If no argument is provided or rootpd is passed, it will connect to root PD on ADSP.

Functionality:
  rootpd:
    - Exception logging: Facilitates transfer of ADSP process exception logs
      to the HLOS (High-Level Operating System) logging infrastructure for
      effective monitoring and debugging
    - Remote file system access
  audiopd:
    - Memory requirements for audio PD dynamic loading
    - Remote file system access

Options:
  -h, --help              display this help and exit
  <pd_name> <domain>      start daemon for specific PD and domain
                            example: ./adsprpcd rootpd adsp
  <pd_name>               start daemon for specific PD
                            example: ./adsprpcd rootpd
  (no arguments)          start daemon for root PD (default domain)

Note that this daemon runs continuously and automatically restarts on errors.
It exits only when the fastRPC device node is not accessible.

root@qcs9100-ride-sx:/usr/bin# ./cdsprpcd -h
Usage: ./cdsprpcd [OPTION]...
Daemon that establishes a connection to CDSP.
If no argument is provided or rootpd is passed, it will connect to root PD on CDSP.

Functionality:
  rootpd:
    - Exception logging: Facilitates transfer of CDSP process exception logs
      to the HLOS (High-Level Operating System) logging infrastructure for
      effective monitoring and debugging
    - Remote file system access

Options:
  -h, --help              display this help and exit
  <pd_name> <domain>      start daemon for specific PD and domain
                            example: ./cdsprpcd rootpd cdsp (or cdsp1)
  <pd_name>               start daemon for specific PD
                            example: ./cdsprpcd rootpd
  (no arguments)          start daemon for root PD (default domain)

Note that this daemon runs continuously and automatically restarts on errors.
It exits only when the fastRPC device node is not accessible.

root@qcs9100-ride-sx:/usr/bin# ./sdsprpcd -h
Usage: ./sdsprpcd [OPTION]...
Daemon that establishes a connection to SDSP.
If no argument is provided or rootpd is passed, it will connect to root PD on SDSP.

Functionality:
  rootpd:
    - Remote file system access

Options:
  -h, --help              display this help and exit
  <pd_name> <domain>      start daemon for specific PD and domain
                            example: ./sdsprpcd rootpd sdsp
  <pd_name>               start daemon for specific PD
                            example: ./sdsprpcd rootpd
  (no arguments)          start daemon for root PD (default domain)

Note that this daemon runs continuously and automatically restarts on errors.
It exits only when the fastRPC device node is not accessible.

root@qcs9100-ride-sx:/usr/bin# ./gdsprpcd -h
Usage: ./gdsprpcd [OPTION]...
Daemon that establishes a connection to GDSP.
If no argument is provided or rootpd is passed, it will connect to root PD on GDSP.

Functionality:
  rootpd:
    - Exception logging: Facilitates transfer of GDSP process exception logs
      to the HLOS (High-Level Operating System) logging infrastructure for
      effective monitoring and debugging
    - Remote file system access

Options:
  -h, --help              display this help and exit
  <pd_name> <domain>      start daemon for specific PD and domain
                            example: ./gdsprpcd rootpd gdsp0 (or gdsp1)

Note that this daemon runs continuously and automatically restarts on errors.
It exits only when the fastRPC device node is not accessible.

Supersedes #186 due to outdated and stale changes.
Fixes: #141