media: ti-vpe: cal: Move format handling to cal.c and expose helpers

The cal_formats array contain the description of all formats supported
by the hardware. It's currently used by the V4L2 video device operations
only, but will be needed by the CAMERARX subdev code too. Move it from
cal-video.c to cal.c and add helper functions to access it.

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>