selftests/bpf: Add a specific dst port matching

selftests/bpf: Add a specific dst port matching

After this patch:

 #102/1   flow_dissector_classification/ipv4:OK
 #102/2   flow_dissector_classification/ipv4_continue_dissect:OK
 #102/3   flow_dissector_classification/ipip:OK
 #102/4   flow_dissector_classification/gre:OK
 #102/5   flow_dissector_classification/port_range:OK
 #102/6   flow_dissector_classification/ipv6:OK
 #102     flow_dissector_classification:OK
 Summary: 1/6 PASSED, 0 SKIPPED, 0 FAILED

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://patch.msgid.link/20250218043210.732959-5-xiyou.wangcong@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>