drm/i915: Implement color management on bdw/skl/bxt/kbl

Patch based on a previous series by Shashank Sharma.

v2: Do not read GAMMA_MODE register to figure what mode we're in

v3: Program PREC_PAL_GC_MAX to clamp pixel values > 1.0

    Add documentation on how the Broadcast RGB property is affected by CTM

v4: Update contributors

v5: Refactor degamma/gamma LUTs load into a single function

v6: Fix missing intel_crtc variable (bisect issue)

v7: Fix & simplify limited range matrix multiplication (Matt Roper's
    comment)

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Kumar, Kiran S <kiran.s.kumar@intel.com>
Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acknowledged-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458125837-2576-4-git-send-email-lionel.g.landwerlin@intel.com