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/x86_init.c

@@ -70,6 +70,7 @@ struct x86_init_ops x86_init __initdata = {
 		.setup_percpu_clockev	= setup_boot_APIC_clock,
 		.tsc_pre_init		= x86_init_noop,
 		.timer_init		= hpet_time_init,
+		.wallclock_init		= x86_init_noop,
 	},
 
 	.iommu = {