media: renesas: rcar_drif: Drop of_match_ptr()

The device_driver structure's of_match_table field exists
unconditionally, so there's no need for of_match_ptr(). This fixes a
compiler warning when test-compiling on non-OF platforms:

drivers/media/platform/renesas/rcar_drif.c:1470:34: warning: unused variable 'rcar_drif_of_table' [-Wunused-const-variable]
static const struct of_device_id rcar_drif_of_table[] = {
                                 ^

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>