media: vicodec: Add pixel encoding flags to fwht header

Add flags indicating the pixel encoding - yuv/rgb/hsv to
fwht header and to the pixel info. Use it to enumerate
the supported pixel formats.

Signed-off-by: Dafna Hirschfeld <dafna3@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>