IB/ipath: Set CPU affinity early

This change moves around port assignment so that it happens before any
memory is allocated.  This allows memory to be allocated on an appropriate
CPU, which improves performance for users of /dev/ipath.

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