ARM: imx: new Kconfig symbol and feature test macro for DMA on mx1 and mx2

This should be used instead of hard coding the corresponding platforms.
The feature test macro is needed to support different SOCs in a single
kernel image.  While at it rename dma-mx1-mx2 to dma-v1 as mx25 doesn't
use it and so the mx2 part is wrong and move the header to
arch/arm/mach-imx.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index 5edead2..73c70af 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -1,7 +1,11 @@
+config IMX_HAVE_DMA_V1
+	bool
+
 if ARCH_MX1
 
 config SOC_IMX1
 	select CPU_ARM920T
+	select IMX_HAVE_DMA_V1
 	select IMX_HAVE_IOMUX_V1
 	bool
 
@@ -27,12 +31,14 @@
 config SOC_IMX21
 	select CPU_ARM926T
 	select ARCH_MXC_AUDMUX_V1
+	select IMX_HAVE_DMA_V1
 	select IMX_HAVE_IOMUX_V1
 	bool
 
 config SOC_IMX27
 	select CPU_ARM926T
 	select ARCH_MXC_AUDMUX_V1
+	select IMX_HAVE_DMA_V1
 	select IMX_HAVE_IOMUX_V1
 	bool