mmc: Kconfig: Add Arasan SDHCI entry

Add Arasan SDHCI entry to Kconfig and fix all references.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_zybo_defconfig b/configs/zynq_zybo_defconfig
index ebaae49..7c23fec 100644
--- a/configs/zynq_zybo_defconfig
+++ b/configs/zynq_zybo_defconfig
@@ -13,6 +13,7 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_SPL_DM_SEQ_ALIAS=y
+CONFIG_ZYNQ_SDHCI=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_ZYNQ_GEM=y