dt-bindings:iio:health:ti,afe4404: Fix wrong compatible value.

Cut and paste error.

Documentation/devicetree/bindings/iio/health/ti,afe4403.example.dt.yaml:
heart_mon@0: 'spi-max-frequency' does not match any of the regexes:
'pinctrl-[0-9]+'

Reported-by: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Fixes: f494151b

 ("dt-bindings:iio:health:ti,afe4404: txt to yaml conversion")
Link: https://lore.kernel.org/r/20201230121919.238335-1-jic23@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>