memory: ti-emif-pm: Drop of_match_ptr from of_device_id table

The driver can match only via the DT table so the table should be always
used and the of_match_ptr does not have any sense (this also allows ACPI
matching via PRP0001, even though it might be not relevant here).  This
fixes compile warning (!CONFIG_OF with clang):

    drivers/memory/ti-emif-pm.c:238:34: warning:
        unused variable 'ti_emif_of_match' [-Wunused-const-variable]

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20210206111343.19273-1-krzk@kernel.org