WM8524 does not use I2C nor SPI, hence no 'reg' property is used,
so remove the unit address from the bindings example to conform.

This avoids users getting dtc warnings when they copy the
binding example to a real dts file.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>