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 <Patil.Reddy@amd.com>
Signed-off-by: Patil Rajesh Reddy <Patil.Reddy@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20240711052047.1531957-2-Shyam-sundar.S-k@amd.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: Shyam Sundar S K