net: dsa: rtl8366: Skip PVID setting if not requested

We go to lengths to determine whether the PVID should be set
for this port or not, and then fail to take it into account.
Fix this oversight.

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>