x86/apic: allow use of lapic timer early calibration result

x86/apic: allow use of lapic timer early calibration result

lapic timer calibration can be combined with tsc in platform specific
calibration functions. if such calibration result is obtained early,
we can skip the redundant calibration loops.

Change-Id: Ib3e4d7ad168172191ff47f3db4368f9869f6ce68
Signed-off-by: Jacob Pan <jacob.jun.pan@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: Dirk Brandewie <dirk.brandewie@gmail.com>