drm/xe/hwmon: Expose power1_max_interval

drm/xe/hwmon: Expose power1_max_interval

Expose power1_max_interval, that is the tau corresponding to PL1, as a
custom hwmon attribute. Some bit manipulation is needed because of the
format of PKG_PWR_LIM_1_TIME in
PACKAGE_RAPL_LIMIT register (1.x * power(2,y))

v2: Get rpm wake ref while accessing power1_max_interval
v3: %s/hwmon/xe_hwmon/
v4:
 - As power1_max_interval is rw attr take lock in read function as well
 - Refine comment about val to fix point conversion (Andi)
 - Update kernel version and date in doc
v5: Fix review comments (Anshuman)

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030115618.1382200-4-badal.nilawar@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>