* HTS221 STM humidity + temperature sensor

Required properties:
- compatible: should be "st,hts221"
- reg: i2c address of the sensor / spi cs line

Optional properties:
- drive-open-drain: the interrupt/data ready line will be configured
  as open drain, which is useful if several sensors share the same
  interrupt line. This is a boolean property.
  If the requested interrupt is configured as IRQ_TYPE_LEVEL_HIGH or
  IRQ_TYPE_EDGE_RISING a pull-down resistor is needed to drive the line
  when it is not active, whereas a pull-up one is needed when interrupt
  line is configured as IRQ_TYPE_LEVEL_LOW or IRQ_TYPE_EDGE_FALLING.
  Refer to pinctrl/pinctrl-bindings.txt for the property description.
- interrupts: interrupt mapping for IRQ. It should be configured with
  flags IRQ_TYPE_LEVEL_HIGH, IRQ_TYPE_EDGE_RISING, IRQ_TYPE_LEVEL_LOW or
  IRQ_TYPE_EDGE_FALLING.

  Refer to interrupt-controller/interrupts.txt for generic interrupt
  client node bindings.

Example:

hts221@5f {
	compatible = "st,hts221";
	reg = <0x5f>;
	interrupt-parent = <&gpio0>;
	interrupts = <0 IRQ_TYPE_EDGE_RISING>;
};