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/arch/powerpc/sysdev/fsl_rio.c b/arch/powerpc/sysdev/fsl_rio.c
index 8bd8653..6425abe 100644
--- a/arch/powerpc/sysdev/fsl_rio.c
+++ b/arch/powerpc/sysdev/fsl_rio.c
@@ -1332,7 +1332,7 @@
 
 /**
  * fsl_rio_setup - Setup Freescale PowerPC RapidIO interface
- * @dev: of_device pointer
+ * @dev: platform_device pointer
  *
  * Initializes MPC85xx RapidIO hardware interface, configures
  * master port with system-specific info, and registers the