mtd: nand-gpio: Do not override GPIOs if driver uses platform_data but OF is...

mtd: nand-gpio: Do not override GPIOs if driver uses platform_data but OF is enabled in kernel config

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>