[media] adv7180: add support to user controls

Video user controls such as brightness, contrast, saturation, and
hue are now handled.

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Richard Röjfors <richard.rojfors.ext@mocean-labs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>