dt-bindings: input: Add bindings for Azoteq IQS7222A/B/C

This patch adds bindings for the Azoteq IQS7222A/B/C family of
capacitive touch controllers.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220403221659.865997-2-jeff@labundy.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>