drm: Redefine pixel formats

Name the formats as DRM_FORMAT_X instead of DRM_FOURCC_X. Use consistent
names, especially for the RGB formats. Component order and byte order are
now strictly specified for each format.

The RGB format naming follows a convention where the components names
and sizes are listed from left to right, matching the order within a
single pixel from most significant bit to least significant bit.

The YUV format names vary more. For the 4:2:2 packed formats and 2
plane formats use the fourcc. For the three plane formats the
name includes the plane order and subsampling information using the
standard subsampling notation. Some of those also happen to match
the official fourcc definition.

The fourccs for for all the RGB formats and some of the YUV formats
I invented myself. The idea was that looking at just the fourcc you
get some idea what the format is about without having to decode it
using some external reference.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>