x86/platform: Add a wallclock_init func to x86_init.timers ops

Some wall clock devices use MMIO based HW register, this new
function will give them a chance to do some initialization work
before their get/set_time service get called, which is usually
in early kernel boot phase.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/setup.c

@@ -1059,6 +1059,8 @@ void __init setup_arch(char **cmdline_p)
 #endif
 	x86_init.oem.banner();
 
+	x86_init.timers.wallclock_init();
+
 	mcheck_init();
 
 	local_irq_save(flags);