TCP BBR: simplify expression

rsm cannot be NULL, when calling bbr_update_bbr_info().
So no need to check partially for it. No functional change intended.

Reviewed by:		rrs
CID:			1523803
MFC after:		1 week
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D48293

sys/netinet/tcp_stacks/bbr.c

@@ -6712,7 +6712,7 @@ bbr_update_bbr_info(struct tcp_bbr *bbr, struct bbr_sendmap *rsm, uint32_t rtt,
 		bbr_log_rtt_shrinks(bbr, cts, 0, rtt, __LINE__, BBR_RTTS_NEWRTT, 0);
 		bbr_set_reduced_rtt(bbr, cts, __LINE__);
 	}
-	bbr_log_type_bbrrttprop(bbr, rtt, (rsm ? rsm->r_end : 0), uts, cts,
+	bbr_log_type_bbrrttprop(bbr, rtt, rsm->r_end, uts, cts,
 	    match, rsm->r_start, rsm->r_flags);
 	apply_filter_min_small(&bbr->r_ctl.rc_rttprop, rtt, cts);
 	if (old_rttprop != bbr_get_rtt(bbr, BBR_RTT_PROP)) {