IPoIB: Avoid reading an uninitialized member variable

This patch avoids that Coverity reports the following:

    Using uninitialized value port_attr.state when calling printk

Fixes: commit 94232d9c ("IPoIB: Start multicast join process only on active ports")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Erez Shitrit <erezsh@mellanox.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>