IB/hfi1: Insure int mask for in-kernel receive contexts is clear

The only use for the urg interrupt is for priority PSM packets.

There is no reason for this interrupt to be enabled for kernel
contexts.

Reviewed-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>