mlxsw: spectrum_matchall: Restrict sample action to be allowed only on ingress

HW supports packet sampling on ingress only. Check and fail if user
is adding sample on egress.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>