dt-bindings: hwmon: pwm-fan: drop text file

This binding was converted to dtschema a year ago.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240322-hwmon_dtschema-v3-3-6697de2a8228@gmail.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>