drivers: sensor: ti: ina230: Add support for INA236

This commit adds support for INA236 into the existing INA230 driver.
These two chips are similar enough to share most of the code.
The device can be defined the same way as INA230 and we only have
the extra option to select the high-precision mode.

```
ina236: ina236@40 {
		status = "okay";
		compatible = "ti,ina236", "ti,ina230";
		reg = <0x40>;
		adc-mode = "Bus and shunt voltage continuous";
		vbus-conversion-time-us = <1100>;
		vshunt-conversion-time-us = <1100>;
		avg-count = <1>;
		current-lsb-microamps = <1000>;
		rshunt-micro-ohms = <15000>;
		alert-gpios = <&gpiod 0 GPIO_ACTIVE_LOW>;
		high-precision;
	};
```

Signed-off-by: Tomáš Juřena <jurenatomas@gmail.com>