Input: serio - trivial documentation fix

In include/linux/serio.h two different define-series are documented as
"Serio types". However the second series contains defines for the
different protocols.
Signed-off-by: NNiels de Vos <niels.devos@wincor-nixdorf.com>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

include/linux/serio.h

@@ -175,7 +175,7 @@ static inline void serio_unpin_driver(struct serio *serio)
 #define SERIO_8042_XL	0x06
 
 /*
- * Serio types
+ * Serio protocols
  */
 #define SERIO_UNKNOWN	0x00
 #define SERIO_MSC	0x01