osc/rdma: fix test/wait hang

There are differences between how active and passive messages are
accounted for in this component. Active message counts on the sender
side are set to zero before the control message is sent so we do not
have to add one to the expected number of messages or we end up
double counting the control message. This commit should fix that error.

Fixes regression in one-sided/test_rma1

cmr=v1.8:reviewer=jsquyres