msm: ipa: fix for bam_isr crash during TX

Initialize the work member of every TX packet in the chain of
TX packets used on the SW TX data path. This is to ensure that
we always have a valid work item to attempt to queue from BAM
ISR for EOT.

Change-Id: I20cdc5cb0a9dab1a49c4a71ded5bac68a8e8bbca
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>