dt-bindings: perf: fsl-imx-ddr: Add compatible string for i.MX8QM, i.MX8QXP and i...

dt-bindings: perf: fsl-imx-ddr: Add compatible string for i.MX8QM, i.MX8QXP and i.MX8DXL

Add compatible string fsl,imx8qm-ddr-pmu, fsl,imx8qxp-ddr-pmu, which
fallback to fsl,imx8-ddr-pmu and fsl,imx8dxl-db-pmu (for data bus fabric).

Add clocks, clock-names for fsl,imx8dxl-db-pmu and keep the same
restriction for existing compatible strings.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Will Deacon <will@kernel.org>