Add more timestamps in coreboot.

Add more timestamps in coreboot.

This adds a number of timestamps in ramstage and romstage
so we can figure out where execution time goes.

Change-Id: Iea17c08774e623fc1ca3fa4505b70523ba4cbf01
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/749
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>