b43: fix build with CONFIG_SSB_PCIHOST=n

m68k allmodconfig gives

drivers/net/wireless/b43/main.c:251: error: implicit declaration of function 'mmiowb'

because CONFIG_B43=m, CONFIG_SSB_PCIHOST=n.

Might be Kconfig bustage, but this works...

Cc: Michael Buesch <mb@bu3sch.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

include/linux/ssb/ssb.h

@@ -373,6 +373,15 @@ void ssb_pcihost_set_power_state(struct ssb_device *sdev, pci_power_t state)
 	if (sdev->bus->bustype == SSB_BUSTYPE_PCI)
 		pci_set_power_state(sdev->bus->host_pci, state);
 }
+#else
+static inline void ssb_pcihost_unregister(struct pci_driver *driver)
+{
+}
+
+static inline
+void ssb_pcihost_set_power_state(struct ssb_device *sdev, pci_power_t state)
+{
+}
 #endif /* CONFIG_SSB_PCIHOST */