ipq40xx: Use constant to set gpio active low/high

ipq40xx: Use constant to set gpio active low/high

The GPIO configuration in the DTS have as third parameter the active
low/high configuration. This parameter is not easy to parse by humans when
it is only set to 0/1. It is better to use the predefined constants
GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW.

Signed-off-by: Sven Eckelmann <[email protected]>