v4l: Add V4L2_PIX_FMT_NV24 and V4L2_PIX_FMT_NV42 formats

NV24 and NV42 are planar YCbCr 4:4:4 and YCrCb 4:4:4 formats with a
luma plane followed by an interleaved chroma plane.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>