Merge branch 'mlxsw-sampling-fixes'

Ido Schimmel says:

====================
mlxsw: Two sampling fixes

This patchset fixes two bugs in recent sampling submissions.

The first fix, in patch #3, prevents matchall rules with sample action
to be added in front of flower rules on egress. Patches #1-#2 are
preparations meant at avoiding similar bugs in the future. Patch #4 is a
selftest.

The second fix, in patch #5, prevents sampling from being enabled on a
port if already enabled. Patch #6 is a selftest.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>