dt-bindings: input: iqs7222: Reduce 'linux,code' to optional

Following a recent refactor of the driver to properly drop unused
device nodes, the 'linux,code' property is now optional. This can
be useful for applications that define GPIO-mapped events that do
not correspond to any keycode.

Fixes: 44dc42d2 ("dt-bindings: input: Add bindings for Azoteq IQS7222A/B/C")
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/Y1SROIrrC1LwX0Sd@nixie71Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/azoteq,iqs7222.yaml

@@ -473,9 +473,6 @@ patternProperties:
               Specifies whether the event is to be interpreted as a key (1)
               or a switch (5).
 
-        required:
-          - linux,code
-
         additionalProperties: false
 
     dependencies:
@@ -620,9 +617,6 @@ patternProperties:
               GPIO, they must all be of the same type (proximity, touch or
               slider gesture).
 
-        required:
-          - linux,code
-
         additionalProperties: false
 
     required: