msm: ipa4: Fix to configure pending packelist WAN consumer pipe

When coalescing pipe and WAN consumer pipe are configuring case
pending list pointer was not initlizing causing null pointer deference.
Add changes to initialize pending packet list for WAN consumer pipe.

Change-Id: I8daa75522be7f6a1fa5eb60e025992539be4b124
Signed-off-by: Ashok Vuyyuru <avuyyuru@codeaurora.org>