IPoIB/cm: Set correct SG list in ipoib_cm_init_rx_wr()

wr->sg_list should be set to the sge pointer passed in, not
priv->cm.rx_sge.

Reported-by: Hoang-Nam Nguyen <HNGUYEN@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>