net/mlx5e: MPLSoUDP encap, support action vlan pop_eth explicitly

Currently the MPLSoUDP encap offload does the L2 pop implicitly
while adding such action explicitly (vlan eth_push) will cause
the rule to not be offloaded.

Solve it by adding offload support for vlan eth_push in case of
MPLSoUDP decap case.

Flow example:
filter root protocol ip pref 1 flower chain 0
filter root protocol ip pref 1 flower chain 0 handle 0x1
  eth_type ipv4
  dst_ip 2.2.2.22
  src_ip 2.2.2.21
  in_hw in_hw_count 1
        action order 1: vlan  pop_eth pipe
         index 1 ref 1 bind 1
        used_hw_stats delayed

        action order 2: mpls  push protocol mpls_uc label 555 tc 3 ttl 255 pipe
         index 1 ref 1 bind 1
        used_hw_stats delayed

        action order 3: tunnel_key  set
        src_ip 8.8.8.21
        dst_ip 8.8.8.22
        dst_port 6635
        csum
        tos 0x4
        ttl 6 pipe
         index 1 ref 1 bind 1
        used_hw_stats delayed

        action order 4: mirred (Egress Redirect to device bareudp0) stolen
        index 1 ref 1 bind 1
        used_hw_stats delayed

Signed-off-by: Maor Dickman <maord@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>