tty: handle compat PPP ioctls

Multiple tty devices are have tty devices that handle the
PPPIOCGUNIT and PPPIOCGCHAN ioctls. To avoid adding a compat_ioctl
handler to each of those, add it directly in tty_compat_ioctl
so we can remove the calls from fs/compat_ioctl.c.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/tty/tty_io.c

@@ -87,6 +87,7 @@
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/poll.h>
+#include <linux/ppp-ioctl.h>
 #include <linux/proc_fs.h>
 #include <linux/init.h>
 #include <linux/module.h>
@@ -2811,6 +2812,9 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
 #endif
 	case TIOCGSOFTCAR:
 	case TIOCSSOFTCAR:
+
+	case PPPIOCGCHAN:
+	case PPPIOCGUNIT:
 		return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
 	case TIOCCONS:
 	case TIOCEXCL: