dt-bindings: iio: adc: adding MCP3564 ADC

dt-bindings: iio: adc: adding MCP3564 ADC

This is the device tree schema for iio driver for
Microchip family of 153.6 ksps, Low-Noise 16/24-Bit
Delta-Sigma ADCs with an SPI interface (Microchip's
MCP3461, MCP3462, MCP3464, MCP3461R, MCP3462R,
MCP3464R, MCP3561, MCP3562, MCP3564, MCP3561R,
MCP3562R and MCP3564R analog to digital converters).

Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230829154133.40716-2-marius.cristea@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>