ipfw: fix operator error in test

Fix warning spotted by clang on FreeBSD:

source-ipfw.c:241:49: warning: use of logical '||' with constant operand [-Wconstant-logical-operand]
        if (suricata_ctl_flags & (SURICATA_STOP || SURICATA_KILL)) {
                                                ^  ~~~~~~~~~~~~~
source-ipfw.c:241:49: note: use '|' for a bitwise operation
        if (suricata_ctl_flags & (SURICATA_STOP || SURICATA_KILL)) {
                                                ^~
                                                |

Use same logic as the one used in other capture mode.