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/of/device.c b/drivers/of/device.c
index 0d8a064..92de0eb 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -14,7 +14,7 @@
  * @ids: array of of device match structures to search in
  * @dev: the of device structure to match against
  *
- * Used by a driver to check whether an of_device present in the
+ * Used by a driver to check whether an platform_device present in the
  * system is in its list of supported devices.
  */
 const struct of_device_id *of_match_device(const struct of_device_id *matches,