IB/hfi1: Fix memory leak in exception path in get_irq_affinity()

IB/hfi1: Fix memory leak in exception path in get_irq_affinity()

When IRQ affinity is set and the interrupt type is unknown, a cpu
mask allocated within the function is never freed. Fix this memory
leak by allocating memory within the scope where it is used.

Reviewed-by: Mike Marciniszyn <[email protected]>
Reviewed-by: Michael J. Ruhl <[email protected]>
Signed-off-by: Sebastian Sanchez <[email protected]>
Signed-off-by: Dennis Dalessandro <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>