warp: Add USB Mass Storage support

With UMS support we are able to flash the eMMC from U-boot, which is very
convenient.

Add UMS support to make the eMMC flashing process easier.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/board/warp/warp.c b/board/warp/warp.c
index 3b275c2..21ac5e7 100644
--- a/board/warp/warp.c
+++ b/board/warp/warp.c
@@ -21,6 +21,7 @@
 #include <watchdog.h>
 #include <fsl_esdhc.h>
 #include <mmc.h>
+#include <usb.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -82,6 +83,11 @@
 	return fsl_esdhc_initialize(bis, &usdhc_cfg[0]);
 }
 
+int board_usb_phy_mode(int port)
+{
+	return USB_INIT_DEVICE;
+}
+
 int board_early_init_f(void)
 {
 	setup_iomux_uart();