zynq: Enable tftp put command

For saving content of memory via tftp to file.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/configs/zynq-common.h b/include/configs/zynq-common.h
index 3ada295..bafa01b 100644
--- a/include/configs/zynq-common.h
+++ b/include/configs/zynq-common.h
@@ -239,5 +239,6 @@
 #define CONFIG_CMD_PING
 #define CONFIG_CMD_DHCP
 #define CONFIG_CMD_MII
+#define CONFIG_CMD_TFTPPUT
 
 #endif /* __CONFIG_ZYNQ_COMMON_H */