drm/xe/hwmon: Read accepted power limit for CRI

drm/xe/hwmon: Read accepted power limit for CRI

Update xe_hwmon_pcode_read_power_limit() and
xe_hwmon_pcode_rmw_power_limit() to read the accepted power limit for
discrete platforms post CRI.

For platforms before CRI only the last written pcode value was available.
From CRI onwards, pcode exposes a new param2 value 2 that allows reading
the accepted power limit by the hardware.

v2:
 - Read resolved power limit in xe_hwmon_pcode_rmw_power_limit()
   as well. (Badal)
 - Rephrase commit message. (Badal)
 - Add prepare_power_limit_param2() to prepare param2 for mailbox power
   limit read.

Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patch.msgid.link/20260323115836.3737300-1-karthik.poosa@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>