media: allegro: activate v4l2-ctrls only for current codec

These controls are specific to H.264 and shall only be activated, if the
coded format is H.264.

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>