RDMA/nes: Fix adapter reset after PXE boot

After PXE boot, the iw_nes driver does a full reset to ensure the card
is in a clean state.  However, it doesn't wait for firmware to
complete its work before issuing a port reset to enable the ports,
which leads to problems bringing up the ports.

The solution is to wait for firmware to complete its work before
proceeding with port reset.

This bug was flagged by Roland Dreier <rolandd@cisco.com>.

Cc: <stable@kernel.org>
Signed-off-by: Chien Tung <ctung@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>