4x gain ceiling is not enough to capture a decent image in conditions
of total darkness and only a LED light source. Allow a maximum gain
of 32x instead.
This doesn't have any drawback since the image quality in 'normal'
light conditions is the same.
Signed-off-by: NJavier Martin <javier.martin@vista-silicon.com>
Acked-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>