When supporting Rpi Camera v2 Module on the RZ/G2E, found the driver had
some issues with rcar mipi-csi driver. The sensor never entered into LP-11
state.
The powerup sequence in the datasheet[1] shows the sensor entering into
LP-11 in streaming mode, so to fix this issue transitions are performed
from "streaming -> standby" in the probe() after power up.
With this commit the sensor is able to enter LP-11 mode during power up,
as expected by some CSI-2 controllers.