DRM: ARC: PGU: add ARGB8888 format to supported format list

As we ignore first 8 bit of 32 bit pixel value we can add ARGB8888
format as alias of XRGB8888.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
1 file changed