bindings: perf: imx-ddr: add compatible string

Add extra compabile string to support driver.
Signed-off-by: NJoakim Zhang <qiangqing.zhang@nxp.com>
Acked-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201130114202.26057-2-qiangqing.zhang@nxp.comSigned-off-by: NWill Deacon <will@kernel.org>

Documentation/devicetree/bindings/perf/fsl-imx-ddr.yaml

@@ -15,6 +15,9 @@ properties:
       - enum:
           - fsl,imx8-ddr-pmu
           - fsl,imx8m-ddr-pmu
+          - fsl,imx8mq-ddr-pmu
+          - fsl,imx8mm-ddr-pmu
+          - fsl,imx8mn-ddr-pmu
           - fsl,imx8mp-ddr-pmu
       - items:
           - enum: