drm/i915/vdsc: Add function to write in PPS register

Now that we have a function that reads any PPS register based
on intel_dsc_pps enum provided lets create a function that can
write on any PPS.

--v2
-Changes need as PPS enum was dropped
-Remove duplicated code in intel_dsc_write_pps_reg [Jani]

--v3
-Use dsc_split instead of num_vdsc_instances [Ankit]

--v5
-Changes to implement the new dsc_reg array variable passing
[Ankit]

--v7
-Pass no of vdsc instances to get_pps_reg [Ankit]

--v8
-No need for dsc_reg dynamic allocation [Jani]
-Change function to void as no return needs to be sent back

--v9
-Send ARRAY_SIZE(dsc_reg) instead of vdsc_per_pipe [Ankit]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230828054300.560559-6-suraj.kandpal@intel.com