drm/vkms: Add support to 1D gamma LUT

Support a 1D gamma LUT with interpolation for each color channel on the
VKMS driver. Add a check for the LUT length by creating
vkms_atomic_check().

Enable VKMS to run the test igt@kms_plane@pixel-format.

Tested with:
igt@kms_color@gamma
igt@kms_color@legacy-gamma
igt@kms_color@invalid-gamma-lut-sizes

v2:
    - Add interpolation between the values of the LUT (Simon Ser)

v3:
    - s/ratio/delta (Pekka)
    - s/color_channel/channel_value (Pekka)
    - s/lut_area/lut_channel
    - Store the `drm_color_lut`, `lut_length`, and
      `channel_value2index_ratio` inside a struct called `vkms_lut`
      (Pekka)
    - Pre-compute some constants values used through the LUT procedure
      (Pekka)
    - Change the switch statement to a cast to __u16* (Pekka)
    - Make the apply_lut_to_channel_value return the computation result
      (Pekka)

v4:
    - Add a comment explaining that `enum lut_area` depends on the
      layout of `struct drm_color_lut` (Pekka)
    - Remove unused variable (kernel test robot)

v5:
    - Mention that this will make it possible to run the test
      igt@kms_plane@pixel-format (Maíra)
    - s/had/has (Maíra)

Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230709013835.161004-1-arthurgrillo@riseup.net