All callers of locate_vbt just care about the file content and immediately map the rdev for its content. Instead of repeating this in all call sites, move that code to locate_vbt. Change-Id: I5b518e6c959437bd8f393269db7955358a786719 Signed-off-by: Patrick Georgi <pgeorgi@google.com> Reviewed-on: https://review.coreboot.org/21896 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>