msm: ipa: teardown APPS DL WAN pipe in SSR

This change fixes an issue in which APPS DL WAN pipe was not
torn down and potentialy packets were sent to the network stack
after SSR happened and rmnet_ipa has been removed.

CRs-fixed: 750682
Change-Id: I8d737f07529021db26bf6c7567fc1d1608e051a7
Signed-off-by: Sivan Reinstein <sivanr@codeaurora.org>
Acked-by: David Arinzon <darinzon@qti.qualcomm.com>