Input: increase struct ps2dev cmdbuf[] to 8 bytes

Cypress PS/2 Trackpad (drivers/input/mouse/cypress_ps2.c) needs
this larger cmdbuf[] to handle 8-byte packet responses.
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

include/linux/libps2.h

@@ -36,7 +36,7 @@ struct ps2dev {
 	wait_queue_head_t wait;
 
 	unsigned long flags;
-	unsigned char cmdbuf[6];
+	unsigned char cmdbuf[8];
 	unsigned char cmdcnt;
 	unsigned char nak;
 };