Input: atkbd - support Microsoft Natural Elite Pro keyboards

Microsoft Natural Elite Pro keyboard produces unisual response to
the GET ID command - single byte 0xaa (normally keyboards produce
2-byte response). Fail GET ID command so atkbd gets a change to
do alternate probe.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/libps2.h b/include/linux/libps2.h
index 08a450a..f6f301e 100644
--- a/include/linux/libps2.h
+++ b/include/linux/libps2.h
@@ -47,5 +47,6 @@
 int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data);
 int ps2_handle_response(struct ps2dev *ps2dev, unsigned char data);
 void ps2_cmd_aborted(struct ps2dev *ps2dev);
+int ps2_is_keyboard_id(char id);
 
 #endif /* _LIBPS2_H */