Qualcomm QPNP power-on

The qpnp-power-on is a driver which supports the power-on(PON)
peripheral on Qualcomm PMICs. The supported functionality includes
power on/off reason, power-key press/release detection and other PON
features. This peripheral is connected to the host processor via the SPMI
interface.

Required properties:
- compatible:	Must be "qcom,qpnp-power-on"
- reg:		Specifies the SPMI address and size for this PON (power-on) peripheral
- interrupts:	Specifies the interrupt associated with the power-key.

Optional properties:
- qcom,pon-key-enable:		Enable power-key detection. It enables monitoring
				of the KPDPWR_N line (connected to the power-key).
- qcom,pon-key-dbc-delay:	The debouce delay for the power-key interrupt
				specifed in us. The value ranges from 2 seconds
				to 1/64 of a second. Possible values are -
				- 2, 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64
				- Intermediate value is rounded down to the
				nearest valid value.
- qcom,pon-key-pull-up:		The intial state of the KPDPWR_N pin
				(connected to the power-key)
				0 = No pull-up
				1 = pull-up enabled

If any of the above optional property is not defined, the driver will continue
with the default hardware state.

Example:
	qcom,power-on@800 {
		compatible = "qcom,qpnp-power-on";
		reg = <0x800 0x100>;
		interrupts = <0x0 0x8 0x1>;
		qcom,pon-key-enable= <true>;
		qcom,pon-key-pull-up = <true>;
		qcom,pon-key-dbc-delay = <15625>;
	}
