mam: ipa: always add default flt rule at the end

Change the logic in IPA driver to always add the default
catch-all filtering rule at the end.

Change-Id: Id442844226398a66813a7ec59c662afea0af2778
Acked-by: Shihuan Liu <shihuanl@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>