mmc: dw_mmc: Remove redundant of_match_ptr

The data structure of_match_ptr() protects is always compiled in.
Hence of_match_ptr() is not needed.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Chris Ball <chris@printf.net>