media: bcm2835-unicam: Fix build with !PM

The driver can only match the device vide the DT table, so the table
should always be used, of_match_ptr does not make sense here.

It fixes this warning:
drivers/media/platform/broadcom/bcm2835-unicam.c:2724:34: warning: ‘unicam_of_match’ defined but not used [-Wunused-const-variable=]

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>