media: synopsys: VIDEO_DW_MIPI_CSI2RX should depend on ARCH_ROCKCHIP

media: synopsys: VIDEO_DW_MIPI_CSI2RX should depend on ARCH_ROCKCHIP

The Synopsys DesignWare MIPI CSI-2 Receiver is currently only supported
on Rockchip RK3568 SoCs.  Hence add a dependency on ARCH_ROCKCHIP, to
prevent asking the user about this driver when configuring a kernel
without Rockchip platform support.

The dependency can be relaxed later, when adding support for appropriate
SoCs from other vendors (if any).

Fixes: 355a110040665e43 ("media: synopsys: add driver for the designware mipi csi-2 receiver")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Michael Riesch <michael.riesch@collabora.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>