V4L/DVB (7178): Add two new fourcc codes for 16bpp formats

This adds two new fourcc codes (as per info at fourcc.org)
for 16bpp mono and 16bpp Bayer formats.

Signed-off-by: Steven Whitehouse <steve@chygwyn.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>