[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>

drivers/spi/Kconfig

@@ -118,7 +118,7 @@ config SPI_GPIO
 
 config SPI_IMX
 	tristate "Freescale iMX SPI controller"
-	depends on ARCH_IMX && EXPERIMENTAL
+	depends on ARCH_MX1 && EXPERIMENTAL
 	help
 	  This enables using the Freescale iMX SPI controller in master
 	  mode.