mtd: denali_dt: Remove redundant use of of_match_ptr

Since this driver is dt only and denali_nand_dt_ids is always
compiled in, use of of_match_ptr() macro is not necessary.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>