net: dsa: rtl8366rb: Move LED blink init to LED code

The code was setting up 56ms blink rate unconditionally,
but now that we have separate LED support code, let's do
it there while waiting for someone to come along and
implement proper HW trigger handling for these LEDs.

Reported-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>