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_mpc8xxx.c b/drivers/spi/spi_mpc8xxx.c
index aad9ae1..d31b57f 100644
--- a/drivers/spi/spi_mpc8xxx.c
+++ b/drivers/spi/spi_mpc8xxx.c
@@ -1236,7 +1236,7 @@
 	return 0;
 }
 
-static int __devinit of_mpc8xxx_spi_probe(struct of_device *ofdev,
+static int __devinit of_mpc8xxx_spi_probe(struct platform_device *ofdev,
 					  const struct of_device_id *ofid)
 {
 	struct device *dev = &ofdev->dev;
@@ -1308,7 +1308,7 @@
 	return ret;
 }
 
-static int __devexit of_mpc8xxx_spi_remove(struct of_device *ofdev)
+static int __devexit of_mpc8xxx_spi_remove(struct platform_device *ofdev)
 {
 	int ret;