gpu: ipu-v3: Add CSI and SMFC module enable wrappers

IPU_CONF_..._EN bits are implementation details, not to be made public.
Add wrappers around ipu_module_enable/disable, so the CSI V4L2 driver
can enable/disable the CSI and SMFC modules.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>