media: imx-pxp: Remove unneeded of_match_ptr()

i.MX is a DT-only platform, so of_match_ptr() can be safely
removed.

Remove the unneeded of_match_ptr().

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>