mtd: Fix dependencies for !HAS_IOMEM archs

Not every arch has io memory.
So, unbreak the build by fixing the dependencies.

Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index 0dc9275..83befab 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -9,6 +9,7 @@
 
 config MTD_MT81xx_NOR
 	tristate "Mediatek MT81xx SPI NOR flash controller"
+	depends on HAS_IOMEM
 	help
 	  This enables access to SPI NOR flash, using MT81xx SPI NOR flash
 	  controller. This controller does not support generic SPI BUS, it only