datapath: change nf_connlabels_get bit arg to 'highest used'

datapath: change nf_connlabels_get bit arg to 'highest used'

Upstream commit:
    commit adff6c65600000ec2bb71840c943ee12668080f5
    Author: Florian Westphal <fw@strlen.de>
    Date:   Tue Apr 12 18:14:25 2016 +0200

    netfilter: connlabels: change nf_connlabels_get bit arg to 'highest used'

    nf_connlabel_set() takes the bit number that we would like to set.
    nf_connlabels_get() however took the number of bits that we want to
    support.

    So e.g. nf_connlabels_get(32) support bits 0 to 31, but not 32.
    This changes nf_connlabels_get() to take the highest bit that we want
    to set.

    Callers then don't have to cope with a potential integer wrap
    when using nf_connlabels_get(bit + 1) anymore.

    Current callers are fine, this change is only to make folloup
    nft ct label set support simpler.

    Signed-off-by: Florian Westphal <fw@strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
OVS compat code defined nf_connlabels_get() if it was missing.  Now we
redefine it if it is missing, or if it has the old signature.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Jesse Gross <jesse@kernel.org>