dt-bindings: mmc: sdhci-iproc: Add brcm,bcm7211a0-sdhci

Add new compatible string for the legacy sdhci controller on the
BCM7211 family of SoC's.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Link: https://lore.kernel.org/r/20210602192758.38735-1-alcooperx@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>