phy/rockchip: add Innosilicon-based CSI dphy

The CSI dphy found for example on the rk3326/px30 and rk3368 is based
on an IP design from Innosilicon. Add a driver for it.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Link: https://lore.kernel.org/r/20210610212935.3520341-3-heiko@sntech.de


Signed-off-by: Vinod Koul <vkoul@kernel.org>