Instead of repeatedly walking cbfs for the AGESA blob and parsing it cache the resulting dispatcher value. There's only one dispatcher table so use it. The resulting change is that this work is done one time per stage. BUG=b:70401101 TEST=Booted and noted only one lookup per stage. Change-Id: Iaa4aecc384108d66d7c68fc5fb9ac1c3f40da905 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/22789 Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Martin Roth <martinroth@google.com> Reviewed-by: Justin TerAvest <teravest@chromium.org>