rockchip: video: Add support for RK3568 DSI Host

rockchip: video: Add support for RK3568 DSI Host

Add support for DSI Host controller on Rockchip RK3568. This driver
is heavily based on the Rockchip dw_mipi_dsi_rockchip.c driver in
Linux and the stm32_dsi.c driver in U-Boot. It should be easy to add
support for other SoCs as the only missing component from the mainline
driver is setting the VOP big or VOP little (which the rk3568 does
not have).

Driver was tested for use in sending commands to a DSI panel in order
to obtain the panel ID.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>