RDMA/nes: Remove unnecessary memset()

Remove an explicit memset(..., 0, ...) of a 'listener' structure
allocated with kzalloc().

Signed-off-by: Christophe Jaillet <christophe.jaillet@wanadoo.fr>
Acked-by: Faisal Latif <faisal@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>