ARM64: zynqmp: ep: Define minimum sdhci frequency for ep

Define minimum sdhci frequency for ep, as not defining
it causes the divisor to be 2048 as per sd version but
keeping clock very low on ep causes command failures.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

include/configs/xilinx_zynqmp_ep.h

@@ -17,6 +17,7 @@
 
 #define CONFIG_ZYNQ_SDHCI0
 #define CONFIG_ZYNQ_SDHCI_MAX_FREQ	52000000
+#define CONFIG_ZYNQ_SDHCI_MIN_FREQ	(CONFIG_ZYNQ_SDHCI_MAX_FREQ << 9)
 #define CONFIG_ZYNQ_I2C0
 #define CONFIG_SYS_I2C_ZYNQ
 #define CONFIG_ZYNQ_EEPROM