ssb: add locking around gpio register accesses

The GPIOs are access through some registers in the chip common core or
over extif. We need locking around these GPIO accesses, all GPIOs are
accessed through the same registers and parallel writes will cause
problems.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/4590
Acked-by: Florian Fainelli <florian@openwrt.org>

drivers/ssb/main.c

@@ -796,6 +796,7 @@ static int __devinit ssb_bus_register(struct ssb_bus *bus,
 	if (err)
 		goto err_pcmcia_exit;
 	ssb_chipcommon_init(&bus->chipco);
+	ssb_extif_init(&bus->extif);
 	ssb_mipscore_init(&bus->mipscore);
 	err = ssb_fetch_invariants(bus, get_invariants);
 	if (err) {