dt-bindings: mfd: iqs62x: Do not override firmware-name $ref

dtschema package defines firmware-name as string-array, so individual
bindings should not make it a string but instead just narrow the number
of expected firmware file names.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Jeff LaBundy <jeff@labundy.com>
Link: https://lore.kernel.org/r/20240115182042.1610134-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Lee Jones <lee@kernel.org>

Documentation/devicetree/bindings/mfd/iqs62x.yaml

@@ -31,7 +31,7 @@ properties:
     maxItems: 1
 
   firmware-name:
-    $ref: /schemas/types.yaml#/definitions/string
+    maxItems: 1
     description:
       Specifies the name of the calibration and configuration file selected by
       the driver. If this property is omitted, the name is chosen based on the