IB/hfi1: Allow MMU function execution in IRQ context

Future users of the MMU/RB functions might be searching or
manipulating the MMU RB trees in interrupt context. Therefore,
the MMU/RB functions need to be able to run in interrupt
context. This requires that we use the IRQ-aware API for
spin locks.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>