Exit if BPF filter file is specified in IPS mode

This patch adds a check that was missing when specifying BPF filter
from a file. Suricata behavior should have been the same as when
BPF filter is specified on command line and IPS mode is used (ie quit).

PR builds:
- PR build: https://buildbot.suricata-ids.org/builders/regit/builds/109
- PR pcaps: https://buildbot.suricata-ids.org/builders/regit-pcap/builds/48