drm_fourcc: sync drm_fourcc with latest drm-next kernel

Update drm_fourcc.h to include latest changes from drm-next branch.
This brings in AFRC (Arm Fixed-Rate Compression) modifiers.

Generated using make headers_install.
Generated from drm-next branch commit 6880fa6

Signed-off-by: Dennis Tsiang <dennis.tsiang@arm.com>