Narrow check for state change in led driver

[jthomaschewski]

As state is checked with if state, the valid state change to 0 (LED_OFF) is ignored by the driver.
As a result its not possible to use the LED_OFF state in the _state_map of _status_ui.py.

Some people would like to turn of the constant flashing of the LED in ready state (DARK_BEACON) (#2, #15). This changes makes this as easy as changing the ready state in the state_map.

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[jthomaschewski]

I signed it!

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CLAs look good, thanks!

[OlivierBondu]

I would also be interested to have this merged 😄 is there any reason not to ?

[OlivierBondu]

thanks!