libpayload-x86: Add PS2 mouse driver

Make use of i8042 driver to add PS2 mouse driver support.

Tested on Lenovot T500.
The touchpad can be used to drive the mouse cursor.

Change-Id: I4be9c74467596b94d64dfa510824d8722108fe9c
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/18597
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

payloads/libpayload/include/libpayload.h

@@ -203,6 +203,15 @@ int i8042_wait_read_aux(void);
 
 /** @} */
 
+/**
+ * @defgroup i8042 PS2 Mouse functions
+ * @ingroup input
+ * @{
+ */
+void i8042_mouse_init(void);
+void i8042_mouse_disconnect(void);
+/** @} */
+
 /**
  * @defgroup serial Serial functions
  * @ingroup input