tty: linux/gsmmux.h needs linux/types.h

We use __u8 in linux/gsmmux.h, so include linux/types.h to have that
defined.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/gsmmux.h

@@ -3,6 +3,7 @@
 
 #include <linux/if.h>
 #include <linux/ioctl.h>
+#include <linux/types.h>
 
 struct gsm_config
 {