drm/i915: Attach colorspace property and enable modeset

This patch attaches the colorspace connector property to the
hdmi connector. Based on colorspace change, modeset will be
triggered to switch to new colorspace.

Based on colorspace property value create an infoframe
with appropriate colorspace. This can be used to send an
infoframe packet with proper colorspace value set which
will help to enable wider color gamut like BT2020 on sink.

This patch attaches and enables HDMI colorspace, DP will be
taken care separately.

v2: Merged the changes of creating infoframe as well to this
patch as per Maarten's suggestion.

v3: Addressed review comments from Shashank. Separated HDMI
and DP colorspaces as suggested by Ville and Maarten.

v4: Addressed Chris and Ville's review comments, and created a
common colorspace property for DP and HDMI, filtered the list
based on the colorspaces supported by the respective protocol
standard. Handle the default case properly.

v5: Merged the DP handling along with platform colorspace
handling as per Shashank's comments.

v6: Reverted to old design of exposing all colorspaces to
userspace as per Ville's review comment

v7: Fixed a checkpatch complaint, Addressed  Maarten' review
comment, updated the RB from Maarten and Jani's ack.

v8: Moved colorspace AVI Infoframe programming to drm core and
removed from driver as per Ville's suggestion.

v9: Added a check to only allow RGB colorpsaces to be set in
infoframe though the colorspace property. Since there is no output
csc property to control planar formats and it will be added later.
Changes for RGB->YUV conversion inside driver without userspace
knowledge is still supported. This is as per Ville's suggestion.

v10: Fixed an error in if check.

v11: Dropped the check for planar vs RGB and allow all the colorspaces.
Onus will be on userspace to pick whatever pipe output it is able to
drive.

v12: Added Ville's RB.

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1550596381-993-4-git-send-email-uma.shankar@intel.com