net: dsa: rtl8366: Fix VLAN set-up

Alter the rtl8366_vlan_add() to call rtl8366_set_vlan()
inside the loop that goes over all VIDs since we now
properly support calling that function more than once.
Augment the loop to postincrement as this is more
intuitive.

The loop moved past the last VID but called
rtl8366_set_vlan() with the port number instead of
the VID, assuming a 1-to-1 correspondence between
ports and VIDs. This was also a bug.

Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Mauri Sandberg <sandberg@mailfence.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Fixes: d8652956 ("net: dsa: realtek-smi: Add Realtek SMI driver")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>