ofproto-dpif: Correct typo in documentation of rule_dpif_lookup()

This corrects a typo that was added by adcf00ba35a0ce9c
("ofproto/bond: Implement bond megaflow using recirculation").

Cc: Andy Zhou <azhou@nicira.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andy Zhou <azhou@nicira.com>¬