hw/intc/arm_gicv3_its: Implement VMAPP

hw/intc/arm_gicv3_its: Implement VMAPP

Implement the GICv4 VMAPP command, which writes an entry to the vPE
table.

For GICv4.1 this command has extra fields in the command packet
and additional behaviour. We define the 4.1-only fields with the
FIELD macro, but only implement the GICv4.0 version of the command.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220408141550.1271295-10-peter.maydell@linaro.org