IB/ipath: Disable IB link earlier in shutdown sequence

Move the code that shuts down the IB link earlier in the unload
process, to be sure no new packets can arrive while we are unloading.

Signed-off-by: Dave Olson <dave.olson@qlogic.com>
Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>