tshark/wireshark: Fix check ring buffer option for packets
tshark and wireshark did not allow only -b packets:value option, while dumpcap does. This change adds the same check in tshark and wireshark as in dumpcap.
Quick fix for issue mentioned at https://ask.wireshark.org/question/23437/why-does-tshark-b-packetsvalue-not-work/