staging/rdma/hfi1: Prevent host software lock up

If packets stop egressing the hardware link, software can lock up.

Implement a timeout for send context halt recovery.  This patch increases the
timeout for packet egress to 500 us and timer resets to zero if the packet
occupancy changes. Also we bounce the link on time out.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Vennila Megavannan <vennila.megavannan@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>