media: remove unnecessary module_init/exit functions

media: remove unnecessary module_init/exit functions

Three media drivers have unnecessary module_init and module_exit
functions that are empty or just print a message. Remove them. Note
that if a module_init function exists, a module_exit function must also
exist; otherwise, the module cannot be unloaded.

Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>