In order to generate Group0 SGIs, let's add some decoding logic to
access_gic_sgi(), and pass the generating group accordingly.
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>