Initial support

[parthitce]

Initial support of MSPM0 will address the following items,

• hal_ti: including the mspm0 sdk with all needed files and independent PR in hal_ti repository
• SoC files: SoC files for Gx series and placeholder to add Lx and Cx
• DTS files: Devicetree files for Gx and placeholder for Lx
• UART: Driver with atleast poll in and out functions
• Pinctrl: Way to configure the pin function and other muxing options. Pinctrl dtsi will be placed in appropriate location (either in HAL or in zephyr tree)
• Board: LP-MSPM0G3507 will the initial candidate

[parthitce]

Initial efforts tracked with zephyrproject-rtos#88725