media: staging: phy-rockchip-dphy-rx0: add Rockchip MIPI Synopsys DPHY RX0 driver

Add driver for Rockchip MIPI Synopsys DPHY driver

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>