tests: shell: check for features not available in 5.4

tests: shell: check for features not available in 5.4

5.4 -stable kernels report failures in these tests, this kernel version
is lacking these feature.

The bitshift requirement is needed by this ruleset:

 table ip x {
        set s13 {
                typeof tcp option mptcp subtype
                elements = { mp-join, dss }
        }

        chain y {
                tcp option mptcp subtype @s13 accept
        }
 }

which uses bitshift in its bytecode.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>