net: dsa: realtek: rtl8365mb: add RTL8367S support

Realtek's RTL8367S, a 5+2 port 10/100/1000M Ethernet switch.
It shares the same driver family (RTL8367C) with other models
as the RTL8365MB-VC. Its compatible string is "realtek,rtl8367s".

It was tested only with MDIO interface (realtek-mdio), although it might
work out-of-the-box with SMI interface (using realtek-smi).

This patch was based on an unpublished patch from Alvin Šipraga
<alsi@bang-olufsen.dk>.

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>