Return NULL for top_of_memory when the register has not been set.
TEST=Build and run on Galileo Gen2
Change-Id: I86684044fc282eaa8deda2b5dbd8ab6cae095d72
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 6edb314050
Original-Change-Id: If79cac68c2a64aa9bf3be72d3cfc4c73fceef12b
Original-Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Original-Reviewed-on: https://review.coreboot.org/18802
Original-Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Original-Tested-by: Martin Roth <martinroth@google.com>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/455822
9c1b53dca1