hw/arm/smmuv3: Wired IRQ and GERROR helpers

We introduce some helpers to handle wired IRQs and especially
GERROR interrupt. SMMU writes GERROR register on GERROR event
and SW acks GERROR interrupts by setting GERRORn.

The Wired interrupts are edge sensitive hence the pulse usage.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Prem Mallappa <prem.mallappa@broadcom.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1524665762-31355-6-git-send-email-eric.auger@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>