media: atomisp: gc0310: Add exposure and gain controls

Add exposure and gain controls. This allows controlling
the exposure and gain through standard v4l2 IOCTLs.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>