hw/intc/arm_gic: Fix deactivation of SPI lines

hw/intc/arm_gic: Fix deactivation of SPI lines

Julien reported that he has seen strange behaviour when running
Xen on QEMU using GICv2. When Xen migrates a guest's vCPU from
one pCPU to another while the vCPU is handling an interrupt, the
guest is unable to properly deactivate interrupts.

Looking at it a little closer, our GICv2 model treats
deactivation of SPI lines as if they were PPI's, i.e banked per
CPU core. The state for active interrupts should only be banked
for PPI lines, not for SPI lines.

Make deactivation of SPI lines unbanked, similar to how we
handle writes to GICD_ICACTIVER.

Reported-by: Julien Grall <julien@xen.org>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Message-id: 20240605143044.2029444-2-edgar.iglesias@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>