hw/arm/virt: Set INTx/gsi mapping

hw/arm/virt: Set INTx/gsi mapping

Let's provide the GPEX host bridge with the INTx/gsi mapping. This is
needed for INTx/gsi routing.

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Tushar Jagad <tushar.jagad@linaro.org>
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Tested-by: Feng Kan <fkan@apm.com>
Message-id: 1505296004-6798-3-git-send-email-eric.auger@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>