drm/exynos: remove redundant of_match_ptr

The driver depends on CONFIG_OF, so it is not necessary to use
of_match_ptr here.

Even for drivers that do not depend on CONFIG_OF, it's almost always
better to leave out the of_match_ptr(), since the only thing it can
possibly do is to save a few bytes of .text if a driver can be used both
with and without it. Hence we remove of_match_ptr.

Signed-off-by: Zhu Wang <wangzhu9@huawei.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>