drivers: video: csi: Increase init priority

The CSI needs to be initialized BEFORE the camera sensor to provide
clock to the camera sensor. It is now possible to do so as direct
reference to the sensor via phandle is now removed. There will be
no check failure on the init order anymore when compiling.

Signed-off-by: Phi Bang Nguyen <phibang.nguyen@nxp.com>