[media] vcodec: mediatek: fix odd_ptr_err.cocci warnings

PTR_ERR should access the value just tested by IS_ERR

Generated by: scripts/coccinelle/tests/odd_ptr_err.cocci

CC: Tiffany Lin <tiffany.lin@mediatek.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>