PCI: aardvark: Check return value of generic_handle_domain_irq() when processing INTx IRQ

It is possible that we receive spurious INTx interrupt. Check for the
return value of generic_handle_domain_irq() when processing INTx IRQ.

Link: https://lore.kernel.org/r/20220110015018.26359-6-kabel@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>