AGESA: Add agesa_helper.h header

These definitions do not require AGESA.h include,
and we will eventually remove agesawrapper.h files.

Change-Id: I1b5b78409828aaf2616e177bb54a054960c3869f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/18588
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
43 files changed