zynq: sdhci: Define max clock by macro

zc1571 with silicon can operate on 200MHz maximum frequency. Setup this
frequency by default and fix setting for ep108.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/configs/xilinx_zynqmp_ep.h b/include/configs/xilinx_zynqmp_ep.h
index ed6023a..8bdb5c9 100644
--- a/include/configs/xilinx_zynqmp_ep.h
+++ b/include/configs/xilinx_zynqmp_ep.h
@@ -19,6 +19,7 @@
 #define CONFIG_ZYNQ_GEM_PHY_ADDR0	7
 
 #define CONFIG_ZYNQ_SDHCI0
+#define CONFIG_ZYNQ_SDHCI_MAX_FREQ	52000000
 #define CONFIG_ZYNQ_I2C0
 #define CONFIG_SYS_I2C_ZYNQ
 #define CONFIG_ZYNQ_EEPROM