Revert "sit: reload iphdr in ipip6_rcv"

commit f4eb17e1efe538d4da7d574bedb00a8dafcc26b7 upstream.

This reverts commit b699d0035836f6712917a41e7ae58d84359b8ff9.

As per Eric Dumazet, the pskb_may_pull() is a NOP in this
particular case, so the 'iph' reload is unnecessary.

Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Luca Boccassi <luca.boccassi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>