[MTD] [NAND] GPIO driver depends on ARM... for now.

Not all architectures provide readsb(). We should probably move to using
ioread8_rep() instead.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/Kconfig

@@ -58,7 +58,7 @@ config MTD_NAND_H1900
 
 config MTD_NAND_GPIO
 	tristate "GPIO NAND Flash driver"
-	depends on GENERIC_GPIO
+	depends on GENERIC_GPIO && ARM
 	help
 	  This enables a GPIO based NAND flash driver.