msm: ipa: discard outstanding packets completion on TX after SSR

Due to a new feature/mechanism in IPA2.6L of IPA HOLB mitigation,
after SSR during TX traffic scenarios, the previous outstanding
TX packets are being consumed by IPA, and IPA sends an indication to
the IPA WAN driver that the packets were consumed.
Since they're related to the previous driver instance (IPA WAN driver
is being unregistered and freed in SSR clean-up procedure),
they need to be released immediately and not processed in order to
avoid accessing a stale/invalid IPA WAN driver pointer.

CRs-Fixed: 828602
Change-Id: I158a76fc7b2769f2a3e4aa68545ed35b044812a7
Signed-off-by: Sivan Reinstein <sivanr@codeaurora.org>
Acked-by: David Arinzon <darinzon@qti.qualcomm.com>