regulator: dt-bindings: mediatek,mt6331: Add missing ldo-vio28 vreg

The MT6331 has a "ldo-vio28" regulator but this was missing in the
list: add it to resolve a dtbs_check warning.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patch.msgid.link/20260113110000.36953-4-angelogioacchino.delregno@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: AngeloGioacchino Del Regno

Documentation/devicetree/bindings/regulator/mediatek,mt6331-regulator.yaml

@@ -40,13 +40,13 @@ patternProperties:
 
     unevaluatedProperties: false
 
-  "^ldo-v(dig18|emc33|ibr|mc|mch|mipi|rtc|sim1|sim2|sram|usb10)$":
+  "^ldo-v(dig18|emc33|ibr|io28|mc|mch|mipi|rtc|sim1|sim2|sram|usb10)$":
     type: object
     $ref: regulator.yaml#
 
     properties:
       regulator-name:
-        pattern: "^v(dig18|emc33|ibr|mc|mch|mipi|rtc|sim1|sim2|sram|usb)$"
+        pattern: "^v(dig18|emc33|ibr|io28|mc|mch|mipi|rtc|sim1|sim2|sram|usb)$"
 
     unevaluatedProperties: false