dt-bindings: mmc: brcm,sdhci-brcmstb: Add support for 7216b0

Add 7216b0 with supports CQE, HS400, HS400-ES and SDR104.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Link: https://lore.kernel.org/r/20200113210706.11972-2-alcooperx@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>