nvmf_transport: Remove invalid assertion

This is leftover from an earlier iteration of the code where 'nt' was
not dynamically allocated but was the passed in 'ops' pointer so was
always alive.

Reported by:	Coverity Scan
CID:	 	1545042
Sponsored by:	Chelsio Communications

sys/dev/nvmf/nvmf_transport.c

@@ -292,8 +292,6 @@ nvmf_transport_module_handler(struct module *mod, int what, void *arg)
 			prev = nt;
 		}
 		if (nt == NULL) {
-			KASSERT(nt->nt_active_qpairs == 0,
-			    ("unregistered transport has connections"));
 			sx_xunlock(&nvmf_transports_lock);
 			return (0);
 		}