The core interrupt code expects the irq_set_affinity call to update the
effective affinity for the interrupt. This was not being done, so update
iproc_msi_irq_set_affinity() to do so.

Link: https://lore.kernel.org/r/20200803035241.7737-1-mark.tomlinson@alliedtelesis.co.nz
Fixes: 3bc2b234 ("PCI: iproc: Add iProc PCIe MSI support")
Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>