platform/x86/amd/pmf: Remove update system state document

This commit removes the "pmf.rst" document, which was associated with
the PMF driver that enabled system state updates based on TA output
actions.

The driver now uses existing input events (KEY_SCREENLOCK, KEY_SLEEP,
and KEY_SUSPEND) instead of defining new udev rules in the
"/etc/udev/rules.d/" directory. Consequently, the pmf.rst document is no
longer necessary. Therefore, the pmf.rst documentation is being removed.

Co-developed-by: Patil Rajesh Reddy <[email protected]>
Signed-off-by: Patil Rajesh Reddy <[email protected]>
Signed-off-by: Shyam Sundar S K <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>

Author: Shyam Sundar S K