doc: update supported hardware offloads in mlx5 guide
doc: update supported hardware offloads in mlx5 guide

Function of_set_vlan_vid is wrongly listed twice in table
"Supported hardware offloads".

This patch removes the listing of of_set_vlan_vid under
"Header rewrite", and leaves the listing of of_set_vlan_vid
under "VLAN".

Signed-off-by: Dekel Peled <f1921780d3213ef78965aec36396441d9bf8894c@mellanox.com>
Acked-by: Ori Kam <dd654df5de18ba542acfaea52fe1a0799392087d@mellanox.com>
Acked-by: Viacheslav Ovsiienko <5b8db9bb93a9a9aefc8828f79604d1fe963a53dd@mellanox.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk