rtl930x: Rework per port LED configuration

rtl930x: Rework per port LED configuration

Use led_setX to determine number of LEDs per port. Introduce macros to
calculate register value and shift for particular LED in a particular
set.

Problem with previous implementation is that it uses is10G status to
determine leds per port. However with usxgmii, driver sets 10g, 5g and
2.5g so even though there are only 2 leds per port it selects 4 leds per
port

This implementation relies on configured led_set node.

Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Harshal Gohel <hg@simonwunderlich.de>