netfilter: Fix to MO call issue

Changes to copy the second half of the combined buffer before
splitting the skb. This solves the issue where MO call does
not go through because the second buffer is not correctly
updated.

Change-Id: Ic00d26c5ce1bde3d56b6d141dc581b98f5b355b5
Signed-off-by: Ravinder Konka <rkonka@codeaurora.org>