[POWERPC] bootwrapper: Set timebase_period_ns from dt_fixup_cpu_clocks

This lets udelay() work properly on platforms which use dt_fixup_cpu_clocks.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/devtree.c

@@ -74,6 +74,8 @@ void dt_fixup_cpu_clocks(u32 cpu, u32 tb, u32 bus)
 		if (bus > 0)
 			setprop_val(devp, "bus-frequency", bus);
 	}
+
+	timebase_period_ns = 1000000000 / tb;
 }
 
 void dt_fixup_clock(const char *path, u32 freq)

arch/powerpc/boot/ops.h

@@ -191,4 +191,6 @@ static inline void exit(void)
 	static char _bss_stack[size]; \
 	void *_platform_stack_top = _bss_stack + sizeof(_bss_stack);
 
+extern unsigned long timebase_period_ns;
+
 #endif /* _PPC_BOOT_OPS_H_ */