media: xilinx: csi2rxss: Drop comment blocks for subdev op handlers

The V4L2 subdev operation handlers have short documentation blocks that
merely duplicates information from the V4L2 subdev API documentation.
They offer no value, and are prone to bit-rotting as shown by the
ixcsi2rxss_set_format() documentation being incorrect. Drop them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>