backend-drm: Add support for YUV plane color properties

The drm_color_encoding and drm_color_range enums are used for
YUV->RGB conversion and mirror what EGL_YUV_COLOR_SPACE_HINT_EXT
and EGL_SAMPLE_RANGE_HINT_EXT as well as our `yuva2rgba()`
shader func do. Add the necessary boiler plate for them.

Signed-off-by: Robert Mader <robert.mader@collabora.com>