ARM: mxc: clean up imx-dma device registration

The patch follows the implementation of gpio-mxc device registration
to break the concentrated imx-dma device registration into soc
specific setup function.  Then we can avoid the churn of "#ifdef"
and the cpu_is_mx checking on such a long list, which makes no sense,
considering more soc supports need to be added and we need to support
single image for multiple socs in the long run.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/plat-mxc/devices.c b/arch/arm/plat-mxc/devices.c
index fb166b2..0d6ed31 100644
--- a/arch/arm/plat-mxc/devices.c
+++ b/arch/arm/plat-mxc/devices.c
@@ -95,8 +95,22 @@
 	.parent		= &platform_bus,
 };
 
+struct device mxc_ahb_bus = {
+	.init_name	= "mxc_ahb",
+	.parent		= &platform_bus,
+};
+
 static int __init mxc_device_init(void)
 {
-	return device_register(&mxc_aips_bus);
+	int ret;
+
+	ret = device_register(&mxc_aips_bus);
+	if (IS_ERR_VALUE(ret))
+		goto done;
+
+	ret = device_register(&mxc_ahb_bus);
+
+done:
+	return ret;
 }
 core_initcall(mxc_device_init);