rockchip: video: mipi: Split mipi driver into common and specific parts

To compatible with different rockchip soc, we split the mipi dirver into
common and soc specific parts, and all the soc share the common
functions from common driver part.

Signed-off-by: Eric Gao <eric.gao@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[agust: fix build breakage and warnings]
Signed-off-by: Anatolij Gustschin <agust@denx.de>