mtd: atmel_nand: fix the warning when CONFIG_OF is not defined
This patch fix following warning:
drivers/mtd/nand/atmel_nand.c:2007: warning: 'atmel_nand_nfc_match' defined but not used
This patch add '#if defined(CONFIG_OF)' block to guard around the definition of
atmel_nand_nfc_match, in order to avoid the warning when kernel is configurated
as non-dt supported.