compat_ioctl: move drivers to compat_ptr_ioctl

Each of these drivers has a copy of the same trivial helper function to
convert the pointer argument and then call the native ioctl handler.

We now have a generic implementation of that, so use it.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/hwtracing/stm/core.c

@@ -832,23 +832,13 @@ stm_char_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return err;
 }
 
-#ifdef CONFIG_COMPAT
-static long
-stm_char_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
-{
-	return stm_char_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
-}
-#else
-#define stm_char_compat_ioctl	NULL
-#endif
-
 static const struct file_operations stm_fops = {
 	.open		= stm_char_open,
 	.release	= stm_char_release,
 	.write		= stm_char_write,
 	.mmap		= stm_char_mmap,
 	.unlocked_ioctl	= stm_char_ioctl,
-	.compat_ioctl	= stm_char_compat_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
 	.llseek		= no_llseek,
 };