realtek: rtl931x: fix setting number of leds per port

realtek: rtl931x: fix setting number of leds per port

In rtl931x_led_init, the number of leds per port is not properly set. It
currently uses a hardcoded value of 1 which seems to be taken initially
from a specific device. This hardcoded value assumes any port always has
exactly two leds.

The RTL930x variant - rtl930x_led_init - does a better job at this. So
take it and use it for RTL931x too with the corresponding register.
While at it, rename the function to a proper naming scheme.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/19241
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>