T60: fix touchpad option

Code used 'int' as return type, but the cmos option is only one
bit. get_option returned with the value in bit 0-7, but all remaining
bits were left unitialized by get_option(). fix this by using char
as type.

Change-Id: I60e609164277380f936f66c99ef9508fa6a6b67c
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/5
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/mainboard/lenovo/t60/mainboard.c

@@ -39,7 +39,7 @@
 static void mainboard_enable(device_t dev)
 {
 	device_t dev0, idedev;
-	int touchpad;
+	u8 touchpad;
 
 	/* enable Audio */
 	h8_set_audio_mute(0);