drm/i915/xelpd: Enable Pipe color support for D13 platform

Enable pipe color support for Display 13 platforms. Currently
limit to just 10bit gamma and later extend it for logarithmic
gamma, once the new UAPI is agreed by community and implemented
by a userspace consumer.

v2: Updated dev_priv to i915 (Ville)

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211207071135.3660332-2-uma.shankar@intel.com