media: allegro: write correct colorspace into SPS

Currently, the driver always writes PAL as video format into the SPS of
the encoded stream.

Set the video format to the default value 5 (unspecified) and use the
color description that is already configured on the channel as color
space. This fixes the color space definition in the coded data to
reflect the configured color space of the video data that is encoded.

Add lookup functions to convert the color primaries, transfer function
and matrix coefficients from the V4L2 control values to the values
specified in the h.264 standard.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>