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/net/greth.h b/drivers/net/greth.h
index 973388d..03ad903 100644
--- a/drivers/net/greth.h
+++ b/drivers/net/greth.h
@@ -118,7 +118,7 @@
 
 	int irq;
 
-	struct device *dev;	        /* Pointer to of_device->dev */
+	struct device *dev;	        /* Pointer to platform_device->dev */
 	struct net_device *netdev;
 	struct napi_struct napi;
 	spinlock_t devlock;