drm/i915/display: Add macro to compare gamma hw/sw lut

Add macro to compare hw/sw gamma lut values. First need to
check whether hw/sw gamma mode matches or not. If not
no need to compare lut values, if matches then only compare
lut entries.

v5: -Called PIPE_CONF_CHECK_COLOR_LUT inside if (!adjust) [Jani]
    -Added #undef PIPE_CONF_CHECK_COLOR_LUT [Jani]
v8: -Added check for gamma mode before gamma lut entry comparison
     [Jani]
    -Split patch 3 into 4 patches

Signed-off-by: Swati Sharma <swati2.sharma@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1567538578-4489-5-git-send-email-swati2.sharma@intel.com