dt-bindings: mmc: remove identical phrase in disable-wp text

There are two identical phrases in the disable-wp text,
so remove one of them.
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mmc/mmc-controller.yaml

@@ -96,8 +96,7 @@ properties:
     description:
       When set, no physical write-protect line is present. This
       property should only be specified when the controller has a
-      dedicated write-protect detection logic. If a GPIO is always
-      used for the write-protect detection. If a GPIO is always used
+      dedicated write-protect detection logic. If a GPIO is always used
       for the write-protect detection logic, it is sufficient to not
       specify the wp-gpios property in the absence of a write-protect
       line.