[media] mt9v022: support required register settings in snapshot mode

Some camera systems cannot operate mt9v022 in normal mode and use
only the snapshot mode. The TechNote for mt9v022 (TN0960) and mt9v024
(TN-09-225) describes required register settings when configuring the
snapshot operation. The snapshot mode requires that certain automatic
functions of the image sensor should be disabled or set to fixed values.
According to the TechNote bit 2 and bit 9 in the register 0x20 must be
set in snapshot mode and unset for normal operation. This applies for
mt9v022 Rev.3 and mt9v024. Add required reg. 0x20 settings dependent on
sensor chip version.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>