vfio/mdev: make create attribute static

The create attribute is not exported, so make it
static to avoid the following sparse warning:

drivers/vfio/mdev/mdev_sysfs.c:77:1: warning: symbol 'mdev_type_attr_create' was not declared. Should it be static?

Signed-off-by: Ben Dooks (Codethink) <ben.dooks@codethink.co.uk>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/mdev/mdev_sysfs.c

@@ -74,7 +74,7 @@ static ssize_t create_store(struct kobject *kobj, struct device *dev,
 	return count;
 }
 
-MDEV_TYPE_ATTR_WO(create);
+static MDEV_TYPE_ATTR_WO(create);
 
 static void mdev_type_release(struct kobject *kobj)
 {