The vendor has marked the RF filter enable control as reserved in
the datasheet; remove it from the binding.

Fixes: 44dc42d2 ("dt-bindings: input: Add bindings for Azoteq IQS7222A/B/C")
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Link: https://lore.kernel.org/r/20220626072412.475211-8-jeff@labundy.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>