dt-bindings: mmc: fsl,esdhc: Add explicit reference to mmc-controller-common

dt-bindings: mmc: fsl,esdhc: Add explicit reference to mmc-controller-common

Even though it is referenced by mmc/mmc-controller.yaml it still raises
the warning:
  esdhc@1560000 (fsl,ls1021a-esdhc): Unevaluated properties are not allowed ('bus-width' was unexpected)

Adding an explicit reference fixes this.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250725060152.262094-1-alexander.stein@ew.tq-group.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>