media: ov5640: Don't force the auto exposure state at start time

The sensor needs to have the auto exposure stopped while changing mode.
However, when the new mode is set, the driver will force the auto exposure
on, disregarding whether the control has been changed or not.

Bypass the controls code entirely to do that, and only use the control
value cached when restoring the auto exposure mode.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>