media: imx-pxp: Fix ERR_PTR dereference in pxp_probe()

media: imx-pxp: Fix ERR_PTR dereference in pxp_probe()

devm_regmap_init_mmio() can fail, add a check and bail out in case of
error.

Fixes: 4e5bd3fdbeb3 ("media: imx-pxp: convert to regmap")
Cc: stable@vger.kernel.org
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20240514095038.3464191-1-harshit.m.mogalapalli@oracle.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>