dt-bindings: input: matrix_keypad: add settle time after enabling all columns

Matrix keypads with high capacity need a longer settle time after
enabling all columns. Add an optional property to specify the settle
time.

Signed-off-by: Markus Burri <markus.burri@mt.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Manuel Traut <manuel.traut@mt.com>
Link: https://lore.kernel.org/r/20250110054906.354296-6-markus.burri@mt.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: Markus Burri

Documentation/devicetree/bindings/input/gpio-matrix-keypad.yaml

@@ -51,6 +51,12 @@ properties:
       before we can scan keypad after activating column gpio.
     default: 0
 
+  all-cols-on-delay-us:
+    description:
+      Delay, measured in microseconds, that is needed
+      after activating all column gpios.
+    default: 0
+
   drive-inactive-cols:
     type: boolean
     description: