ARM: zynq: Added USB host support for zynq boards

Added configs to support USB host for zynq boards.
Also added a command usbboot to boot from usb.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/configs/zynq_zed.h b/include/configs/zynq_zed.h
index 274140c..ce17d40 100644
--- a/include/configs/zynq_zed.h
+++ b/include/configs/zynq_zed.h
@@ -18,6 +18,7 @@
 
 #define CONFIG_SYS_NO_FLASH
 
+#define CONFIG_ZYNQ_USB
 #define CONFIG_ZYNQ_SDHCI0
 #define CONFIG_ZYNQ_BOOT_FREEBSD
 #define CONFIG_DEFAULT_DEVICE_TREE	zynq-zed