ipacm: Add flag to get previous mux id

Add flag to get previous mux id and delete rule
for correct PDN.

Change-Id: Id55ba3d2c0c79121ccf4e8f74e017e10bf82acc7
Acked-by: Pooja Kumari <kumarip@qti.qualcomm.com>
Signed-off-by: Mohammed Javid <mjavid@codeaurora.org>