ipq806x: more dts cleanup

ipq806x: more dts cleanup

Remove the wifi5g LED from the the d7800, r7500 and r7800. Albeit this
GPIO is mentioned in the GPL tarball, it doesn't do anything. The
2.4/5 GHz LEDs are connected to the wifi chips and not be controlled
from the the userspace.

Use the LEDs names/colours as they are used in the board manuals. Merge
redundant LED configurations. Use the phy[0|1]tpt trigger for the
wireless LEDs. Remove the workarounds for the not controllable wireless
LEDs.

Fix spi compatible strings and remove superfluous spi-max-frequency
parameters.

If there are two power leds, use one for indicating normal operation and
one for failsafe/upgrade. Keep the on/off state of the main power led
during boot.

Use the usb pinmux settings from the nbg6817 gpl sources.

Signed-off-by: Mathias Kresin <dev@kresin.me>