hw/intc/arm_gicv3_its: Implement VMAPI and VMAPTI

hw/intc/arm_gicv3_its: Implement VMAPI and VMAPTI

Implement the GICv4 VMAPI and VMAPTI commands. These write
an interrupt translation table entry that maps (DeviceID,EventID)
to (vPEID,vINTID,doorbell). The only difference between VMAPI
and VMAPTI is that VMAPI assumes vINTID == EventID rather than
both being specified in the command packet.

(This code won't be reachable until we allow the GIC version to be
set to 4.  Support for reading this new virtual-interrupt DTE and
handling it correctly will be implemented in a later commit.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220408141550.1271295-9-peter.maydell@linaro.org