datapath: Replace nf_ct_invert_tuplepr() with nf_ct_invert_tuple()

datapath: Replace nf_ct_invert_tuplepr() with nf_ct_invert_tuple()

After upstream net-next commit 303e0c558959 ("netfilter: conntrack:
avoid unneeded nf_conntrack_l4proto lookups") nf_ct_invert_tuplepr()
is no longer available in the kernel.

Ideally, we should be in sync with upstream kernel by calling
nf_ct_invert_tuple() directly in conntrack.c.  However,
nf_ct_invert_tuple() has different function signature in older kernel,
and it would be hard to replace that in the compat layer. Thus, we
use rpl_nf_ct_invert_tuple() in conntrack.c and maintain compatibility
in the compat layer so that ovs kernel module runs smoothly in both
new and old kernel.

Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Reviewed-by: Yifeng Sun <pkusunyifeng@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>