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>

arch/powerpc/platforms/83xx/mpc837x_mds.c

@@ -102,7 +102,7 @@ static struct of_device_id mpc837x_ids[] = {
 
 static int __init mpc837x_declare_of_platform_devices(void)
 {
-	/* Publish of_device */
+	/* Publish platform_device */
 	of_platform_bus_probe(NULL, mpc837x_ids, NULL);
 
 	return 0;

arch/powerpc/platforms/83xx/mpc837x_rdb.c

@@ -78,7 +78,7 @@ static struct of_device_id mpc837x_ids[] = {
 
 static int __init mpc837x_declare_of_platform_devices(void)
 {
-	/* Publish of_device */
+	/* Publish platform_device */
 	of_platform_bus_probe(NULL, mpc837x_ids, NULL);
 
 	return 0;