Input: ALPS - fix forward/back buttons reversed on Acer 5520-5290

ALPS_FW_BK_1 protocol flavor seems to have forward and backward
keys reversed.
Signed-off-by: NLaszlo Kajan <kajla@bioinfo.pl>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

drivers/input/mouse/alps.c

@@ -116,8 +116,8 @@ static void alps_process_packet(struct psmouse *psmouse)
 	}
 
 	if (priv->i->flags & ALPS_FW_BK_1) {
-		back = packet[2] & 4;
-		forward = packet[0] & 0x10;
+		back = packet[0] & 0x10;
+		forward = packet[2] & 4;
 	}
 
 	if (priv->i->flags & ALPS_FW_BK_2) {