dt-bindings: mmc: mmci: add delay block base register for sdmmc

dt-bindings: mmc: mmci: add delay block base register for sdmmc

To support the sdr104 mode, the sdmmc variant has a hardware delay block to
manage the clock phase when sampling data received by the card.

This patch adds a second base register (optional) for sdmmc delay block.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200128090636.13689-6-ludovic.barre@st.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>