of/device: Replace struct of_device with struct platform_device

of_device is just an alias for platform_device, so remove it entirely.  Also
replace to_of_device() with to_platform_device() and update comment blocks.

This patch was initially generated from the following semantic patch, and then
edited by hand to pick up the bits that coccinelle didn't catch.

@@
@@
-struct of_device
+struct platform_device

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c
index 14a8c0f..4e9cbf3 100644
--- a/drivers/dma/mpc512x_dma.c
+++ b/drivers/dma/mpc512x_dma.c
@@ -627,7 +627,7 @@
 	return &mdesc->desc;
 }
 
-static int __devinit mpc_dma_probe(struct of_device *op,
+static int __devinit mpc_dma_probe(struct platform_device *op,
 					const struct of_device_id *match)
 {
 	struct device_node *dn = op->dev.of_node;
@@ -753,7 +753,7 @@
 	return retval;
 }
 
-static int __devexit mpc_dma_remove(struct of_device *op)
+static int __devexit mpc_dma_remove(struct platform_device *op)
 {
 	struct device *dev = &op->dev;
 	struct mpc_dma *mdma = dev_get_drvdata(dev);