hw/arm/xlnx: Connect secondary CGEM IRQs

hw/arm/xlnx: Connect secondary CGEM IRQs

The Cadence GEM peripherals as configured for Zynq MPSoC and Versal
platforms have two priority queues with separate interrupt sources for
each. If the interrupt source for the second priority queue is not
connected, they work in polling mode only. This change connects the
second interrupt source for platforms where it is available. This patch
has been tested using the lwIP stack with a Xilinx-supplied driver from
their embeddedsw repository.

Signed-off-by: Kinsey Moore <kinsey.moore@oarcorp.com>
Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>