gpio-ir-overlay: add parameter to configure signal polarity (#3490)

Standard IR receivers use inverted / active-low signalling
and the gpio-ir overlay configures the GPIO appropriately
as GPIO_ACTIVE_LOW (1).

In order to support (rather rare) non-inverted / active-high
signalling the GPIO needs to be configured as GPIO_ACTIVE_HIGH (0).

Add an "invert" parameter to override this like in the gpio-ir-tx
overlay.

Signed-off-by: Matthias Reichl <hias@horus.com>