soc: ti: QMSS: Fix usage of irq_set_affinity_hint

The Keystone QMSS driver is pretty damaged, in the sense that it
does things like this:

	irq_set_affinity_hint(irq, to_cpumask(&cpu_map));

where cpu_map is a local variable. As we leave the function, this
will point to nowhere-land, and things will end-up badly.

Instead, let's use a proper cpumask that gets allocated, giving
the driver a chance to actually work with things like irqbalance
as well as have a hypothetical 64bit future.

Cc: stable@vger.kernel.org
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Olof Johansson <olof@lixom.net>