[media] s5p-mfc: Remove redundant use of of_match_ptr macro

'exynos_mfc_match' is always compiled in. Hence of_match_ptr
is unnecessary.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>