ramips: timecloud: fix LED configs

ramips: timecloud: fix LED configs

The LED(s) does not have a label for status, ethernet, or whatsoever.

These two LEDs, are used to form one dual-color indicator. On vendor
firmware, the light is turned from orange to white, when external
storage is detected and ready to use. However, if we use white for any
other triggers (USB / SD card / ethernet), it is difficult to see while
the orange is on. Thus, we change led-running to white to indicate a
successful startup.

Also add the missing pinmux config for uart3 since LEDs take GPIO 7 and
8.

Signed-off-by: David Yang <mmyangfl@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23182
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>