drm/i915/xelpd: Calculate VDSC RC parameters

Add methods to calculate rc parameters for all bpps, against the fixed
arrays that we already have for 8,10,12 valid o/p bpps, to cover RGB 444
formats.  Our hw doesn't support YUV compression yet.  The calculations
used here are from VESA C model for DSC 1.1

v2:
 - Checkpatch fixes

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Juha-Pekka Heikkil <juha-pekka.heikkila@intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Mohammed Khajapasha <mohammed.khajapasha@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210519000625.3184321-2-lucas.demarchi@intel.com