V4L/DVB (10078): video: add NV16 and NV61 pixel formats

This patch adds support for NV16 and NV61 pixel formats.

These pixel formats use two planes; one for 8-bit Y values and
one for interleaved 8-bit U and V values. NV16/NV61 formats are
very similar to NV12/NV21 with the exception that NV16/NV61 are
using the same number of lines for both planes. The difference
between NV16 and NV61 is the U and V byte order.

The fourcc values are extrapolated from the NV12/NV21 case.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>