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/watchdog/riowd.c b/drivers/watchdog/riowd.c
index 4082b4a..3faee1a 100644
--- a/drivers/watchdog/riowd.c
+++ b/drivers/watchdog/riowd.c
@@ -172,7 +172,7 @@
 	.fops	= &riowd_fops
 };
 
-static int __devinit riowd_probe(struct of_device *op,
+static int __devinit riowd_probe(struct platform_device *op,
 				 const struct of_device_id *match)
 {
 	struct riowd *p;
@@ -219,7 +219,7 @@
 	return err;
 }
 
-static int __devexit riowd_remove(struct of_device *op)
+static int __devexit riowd_remove(struct platform_device *op)
 {
 	struct riowd *p = dev_get_drvdata(&op->dev);