[media] mt9v022: add v4l2 controls for blanking

Add controls for horizontal and vertical blanking. Also add an error
message for case that the control handler init failed. Since setting
the blanking registers is done by controls now, we shouldn't change
these registers outside of the control function. Use v4l2_ctrl_s_ctrl()
to set them.

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>