Implement the timer_monotonic_get() using the TSC. Change-Id: I5118da6fb9bccc75d2ce012317612e0ab20a2cac Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: http://review.coreboot.org/3155 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>