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>

sound/aoa/soundbus/sysfs.c

@@ -16,7 +16,7 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
 	struct soundbus_dev *sdev = to_soundbus_device(dev);
-	struct of_device *of = &sdev->ofdev;
+	struct platform_device *of = &sdev->ofdev;
 	int length;
 
 	if (*sdev->modalias) {