media: staging: tegra-vde: Factor out H.264 code

Factor out H.264 hardware programming code into separate source file in a
preparation to support V4L API by the Tegra video decoder driver.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>