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/char/hw_random/n2rng.h b/drivers/char/hw_random/n2rng.h
index a2b81e7..4bea07f 100644
--- a/drivers/char/hw_random/n2rng.h
+++ b/drivers/char/hw_random/n2rng.h
@@ -65,7 +65,7 @@
 };
 
 struct n2rng {
-	struct of_device	*op;
+	struct platform_device	*op;
 
 	unsigned long		flags;
 #define N2RNG_FLAG_VF		0x00000001 /* Victoria Falls RNG, else N2 */