ssb: get alp clock from devices with PMU

If there is a PMU in the device, get the alp clock from that part and
do not assume 20000000.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/ssb/ssb_private.h

@@ -210,5 +210,6 @@ static inline void b43_pci_ssb_bridge_exit(void)
 /* driver_chipcommon_pmu.c */
 extern u32 ssb_pmu_get_cpu_clock(struct ssb_chipcommon *cc);
 extern u32 ssb_pmu_get_controlclock(struct ssb_chipcommon *cc);
+extern u32 ssb_pmu_get_alp_clock(struct ssb_chipcommon *cc);
 
 #endif /* LINUX_SSB_PRIVATE_H_ */