msm: ipa: Fix to incorrect dl stats

DL stats from Q6 include the additional LAN/WLAN
header bytes for respective endpoint. Make a change to
deduct the header bytes to keep the stats
accurate.

Reverting the changes done as part of
commit id:98022549

Change-Id: I50683cd3c9b00794292dfb241293356d4566d39e
Signed-off-by: Mohammed Javid <mjavid@codeaurora.org>