regulator: dt-bindings: samsung,s2mps14: add lost samsung,ext-control-gpios

The samsung,ext-control-gpios property was lost during conversion to DT
schema:

exynos3250-artik5-eval.dtb: pmic@66: regulators:LDO11: Unevaluated properties are not allowed ('samsung,ext-control-gpios' was unexpected)

Fixes: ea98b9eba05c ("regulator: dt-bindings: samsung,s2m: convert to dtschema")
Cc: <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/samsung,s2mps14.yaml

···
   additional information and example.
 
 patternProperties:
-  # 25 LDOs
-  "^LDO([1-9]|[1][0-9]|2[0-5])$":
+  # 25 LDOs, without LDO10-12
+  "^LDO([1-9]|1[3-9]|2[0-5])$":
     type: object
     $ref: regulator.yaml#
     unevaluatedProperties: false
     description:
       Properties for single LDO regulator.
+
+    required:
+      - regulator-name
+
+  "^LDO(1[0-2])$":
+    type: object
+    $ref: regulator.yaml#
+    unevaluatedProperties: false
+    description:
+      Properties for single LDO regulator.
+
+    properties:
+      samsung,ext-control-gpios:
+        maxItems: 1
+        description:
+          LDO10, LDO11 and LDO12 can be configured to external control over
+          GPIO.
 
     required:
       - regulator-name