lapic: monotonic time implementation

Implement the timer_monotonic_get() functionality based off of
the local apic timer.

Change-Id: I1aa1ff64d15a3056d6abd1372be13da682c5ee2e
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/3154
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
2 files changed