ASoC: dt-bindings: mt8183: add compatible string for using rt1015p

Machines with rt1015p should use the compatible string
"mt8183-mt6358-ts3a227-rt1015p".
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20210311033151.1818603-2-tzungbi@google.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/mt8183-mt6358-ts3a227-max98357.txt

@@ -4,6 +4,7 @@ Required properties:
 - compatible : "mediatek,mt8183_mt6358_ts3a227_max98357" for MAX98357A codec
                "mediatek,mt8183_mt6358_ts3a227_max98357b" for MAX98357B codec
                "mediatek,mt8183_mt6358_ts3a227_rt1015" for RT1015 codec
+               "mediatek,mt8183_mt6358_ts3a227_rt1015p" for RT1015P codec
 - mediatek,platform: the phandle of MT8183 ASoC platform
 
 Optional properties: