IB/hfi1: Increase packet egress timeout

The current value of 500us for the packet egress timeout is too small
which causes the host to declare failure on draining packets too early
and unnecessarily bounces the link. Increase this to 50ms taking into
account the switch packet discard timer default and the worst case
per-VL package drainage rate.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>