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>

src/mainboard/biostar/am1ml/romstage.c

@@ -28,6 +28,7 @@
 #include <commonlib/loglevel.h>
 #include <cpu/amd/car.h>
 #include <northbridge/amd/agesa/agesawrapper.h>
+#include <northbridge/amd/agesa/agesa_helper.h>
 #include <cpu/x86/bist.h>
 #include <cpu/x86/lapic.h>
 #include <southbridge/amd/common/amd_defs.h>