s390/pci: do not set affinity for floating irqs

s390/pci: do not set affinity for floating irqs

with the introduction of CPU directed interrupts the kernel
parameter pci=force_floating was introduced to fall back
to the previous behavior using floating irqs.

However we were still setting the affinity in that case,
both in __irq_alloc_descs() and via the irq_set_affinity
callback in struct irq_chip.

For the former only set the affinity in the directed case.

The latter is explicitly set in zpci_directed_irq_init()
so we can just leave it unset for the floating case.

Fixes: e979ce7bced2 ("s390/pci: provide support for CPU directed interrupts")
Co-developed-by: Alexander Schmidt <alexs@linux.ibm.com>
Signed-off-by: Alexander Schmidt <alexs@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>