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_zc70x.h b/include/configs/zynq_zc70x.h
index de0e241..291a5fe 100644
--- a/include/configs/zynq_zc70x.h
+++ b/include/configs/zynq_zc70x.h
@@ -19,6 +19,7 @@
 #define CONFIG_SYS_NO_FLASH
 
 #define CONFIG_ZYNQ_SDHCI0
+#define CONFIG_ZYNQ_USB
 #define CONFIG_ZYNQ_I2C0
 #define CONFIG_ZYNQ_EEPROM
 #define CONFIG_ZYNQ_BOOT_FREEBSD