Makefile: Check for errors in ACPI decompilation, too

Makefile: Check for errors in ACPI decompilation, too

We only grep'ed for "ACPI Warning" resulting in an actual more severe
"ACPI Error" being ignored.

Change-Id: I9cec8a388f5558b1ffc383cc2fc69405252cbb37
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32469
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>