compat_ioctl: move WDIOC handling into wdt drivers

All watchdog drivers implement the same set of ioctl commands, and
fortunately all of them are compatible between 32-bit and 64-bit
architectures.

Modern drivers always go through drivers/watchdog/wdt.c as an abstraction
layer, but older ones implement their own file_operations on a character
device for this.

Move the handling from fs/compat_ioctl.c into the individual drivers.

Note that most of the legacy drivers will never be used on 64-bit
hardware, because they are for an old 32-bit SoC implementation, but
doing them all at once is safer than trying to guess which ones do
or do not need the compat_ioctl handling.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/watchdog/watchdog_dev.c

@@ -933,6 +933,7 @@ static const struct file_operations watchdog_fops = {
 	.owner		= THIS_MODULE,
 	.write		= watchdog_write,
 	.unlocked_ioctl	= watchdog_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
 	.open		= watchdog_open,
 	.release	= watchdog_release,
 };