mmc: Add Marvell Xenon SDHCI controller driver

This driver implementes platform specific code for the Xenon SDHCI
controller which is integrated in the Marvell MVEBU Armada 37xx and
Armada 7k / 8K SoCs.

History:
This driver is ported from the Marvell U-Boot version 2015.01 which is
written by Victor Gu <xigu@marvell.com> with minor changes ported from
the Linux driver which is written by Ziji Hu <huziji@marvell.com>.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 9ed8da3..147e52d 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -287,6 +287,17 @@
 
 	  If unsure, say N.
 
+config MMC_SDHCI_XENON
+	bool "SDHCI support for the Xenon SDHCI controller"
+	depends on MMC_SDHCI && DM_MMC && OF_CONTROL
+	help
+	  Support for Xenon SDHCI host controller on Marvell Armada 3700
+	  7k/8k ARM SoCs platforms
+
+	  If you have a controller with this interface, say Y here.
+
+	  If unsure, say N.
+
 config MMC_SDHCI_TEGRA
 	bool "SDHCI platform support for the Tegra SD/MMC Controller"
 	depends on TEGRA