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/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 9967fff..5f67e33 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -487,6 +487,13 @@
 	help
 	  Set the maximum frequency of the controller.
 
+config ZYNQ_SDHCI_MIN_FREQ
+	int "Set the minimum frequency of the controller"
+	depends on MMC_SDHCI_ZYNQ
+	default 0
+	help
+	  Set the minimum frequency of the controller.
+
 config MMC_SUNXI
 	bool "Allwinner sunxi SD/MMC Host Controller support"
 	depends on ARCH_SUNXI && !UART0_PORT_F