dt-bindings: input: iqs269a: Add bindings for OTP variants

This patch adds bindings for the D0 order code of the device. This
order code represents an OTP variant that enables a touch-and-hold
function in place of slider 1.

Also included is the ability to specify the 00 order code (default
option with no OTP customization) explicitly.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/ZZMaW9RkQ9bKXOUn@nixie71


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>