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/spi/spi_ppc4xx.c b/drivers/spi/spi_ppc4xx.c
index 0f5fa7e..80e172d 100644
--- a/drivers/spi/spi_ppc4xx.c
+++ b/drivers/spi/spi_ppc4xx.c
@@ -388,9 +388,9 @@
 }
 
 /*
- * of_device layer stuff...
+ * platform_device layer stuff...
  */
-static int __init spi_ppc4xx_of_probe(struct of_device *op,
+static int __init spi_ppc4xx_of_probe(struct platform_device *op,
 				      const struct of_device_id *match)
 {
 	struct ppc4xx_spi *hw;
@@ -565,7 +565,7 @@
 	return ret;
 }
 
-static int __exit spi_ppc4xx_of_remove(struct of_device *op)
+static int __exit spi_ppc4xx_of_remove(struct platform_device *op)
 {
 	struct spi_master *master = dev_get_drvdata(&op->dev);
 	struct ppc4xx_spi *hw = spi_master_get_devdata(master);