datapath: compat: get rid of OVS_CB inner header offsets.

datapath: compat: get rid of OVS_CB inner header offsets.

OVS has GSO compat functionality which needs inner offset
of the packet to segment a packet. older kernel did not
include these offsets in skb, therefore these were stored
in OVS_GSO_CB. Now OVS has dropped support for these
old kernel, So none of the supported kernel needs this
comapt code. Following patch removes it.

Signed-off-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Jesse Gross <jesse@kernel.org>