Convert the drv260x haptics binding to DT schema format.

The only notable change from .txt format is that vbat-supply is not
actually required, so don't make it a required property.
Acked-by: Andrew Davis <afd@ti.com>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221118174831.69793-1-luca@z3ntu.xyzSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>