netipsec: Fix minor style nit

Coverity points out that 'continue' is equivalent to 'break' in a do {}
while(false) loop.

Reported by:	Coverity
CID:		1354983
Sponsored by:	EMC / Isilon Storage Division

sys/netipsec/key.c

@@ -351,7 +351,7 @@ do { \
 	if ((head) != (sav)) {						\
 		ipseclog((LOG_DEBUG, "%s: state mismatched (TREE=%d SA=%d)\n", \
 			(name), (head), (sav)));			\
-		continue;						\
+		break;							\
 	}								\
 } while (0)