[ARM] Remove arch-imx from build system

arch-imx is superseeded by the MXC architecture support.
This patch removes arch-imx from the build system.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index b4cf691..3eb87bd 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -155,7 +155,7 @@
 
 config MMC_IMX
 	tristate "Motorola i.MX Multimedia Card Interface support"
-	depends on ARCH_IMX
+	depends on ARCH_MX1
 	help
 	  This selects the Motorola i.MX Multimedia card Interface.
 	  If you have a i.MX platform with a Multimedia Card slot,