soc: qcom: bam_dmux: Restore the skb to orginal in write_done

The client skb buffers are updated with bam_dmux transport header
and padding information during bam_dmux write which alters the actual
skb buffers data and length send by the clients.

Remove the bam_dmux header and padding length from skb before notifying
client in the write_done callback.

CRs-Fixed: 689227
Change-Id: If33bd2f7addba8da83742b9337d84ec7b52db525
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>