mmc: Added Kconfig support for CONFIG_ZYNQ_SDHCI_MIN_FREQ

This patch added Kconfig support for CONFIG_ZYNQ_SDHCI_MIN_FREQ
and enabled it in respective defconfig.

Signed-off-by: Vipul Kumar <vipulk@xilinx.com>
Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/xilinx_zynqmp_ep_defconfig b/configs/xilinx_zynqmp_ep_defconfig
index 00db5e3..a0c8f28 100644
--- a/configs/xilinx_zynqmp_ep_defconfig
+++ b/configs/xilinx_zynqmp_ep_defconfig
@@ -62,6 +62,7 @@
 CONFIG_DM_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ZYNQ=y
+CONFIG_ZYNQ_SDHCI_MIN_FREQ=100000
 CONFIG_NAND=y
 CONFIG_NAND_ARASAN=y
 CONFIG_SPI_FLASH=y