Add SDHCI host controller found on STMicroelectronics SoCs
On some ST SoCs, i.e. STiH407/STiH410, the MMC devices can live
inside a dedicated flashSS sub-system that provides an extend subset
of registers that can be used to configure the Arasan MMC/SD Host
Controller.
This means, that the SDHCI Arasan Controller can be configured to be
eMMC4.5 or 4.3 spec compliant.
W/o these settings the SDHCI will configure and use the MMC/SD
controller with limited features e.g. PIO mode, no DMA, no HS etc.
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
