drm/i915/pps: Disable DPLS_GATING around pps sequence

drm/i915/pps: Disable DPLS_GATING around pps sequence

Disable bit 29 of SCLKGATE_DIS register around pps sequence
when we turn panel power on.

--v2
-Squash two commit together [Jani]
-Use IS_DISPLAY_VER [Jani]
-Fix multiline comment [Jani]

--v3
-Define register in a more appropriate place [Mitul]

--v4
-Register is already defined no need to define it again [Ville]
-Use correct WA number (lineage no.) [Dnyaneshwar]
-Fix the range on which this WA is applied [Dnyaneshwar]

Bspec: 49304
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240813042807.4015214-1-suraj.kandpal@intel.com