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/sunhme.h b/drivers/net/sunhme.h
index efd2ca0..756b5bf 100644
--- a/drivers/net/sunhme.h
+++ b/drivers/net/sunhme.h
@@ -407,7 +407,7 @@
 	void (*write_rxd)(struct happy_meal_rxd *, u32, u32);
 #endif
 
-	/* This is either an of_device or a pci_dev. */
+	/* This is either an platform_device or a pci_dev. */
 	void			  *happy_dev;
 	struct device		  *dma_dev;