media: ti-vpe: cal: Split CAMERARX handling to cal-camerarx.c

Implementation of media controller centric device configuration will add
code to the CAMERARX support section, which is already quite big. Move
it to a separate file to make the code more manageable. No functional
change is included.

The cal_camerarx_init_regmap() function is kept in cal.c and renamed to
cal_init_camerarx_regmap() as it's not specific to one CAMERARX
instance, but related to the whole CAL device.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>