usb: reload watchdog during ums command

Reload the watchdog in the mass storage command ums
to avoid reboot during the usb waiting loop
when the host doesn't send any request.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/cmd/usb_mass_storage.c b/cmd/usb_mass_storage.c
index 753ae4f..570cf3a 100644
--- a/cmd/usb_mass_storage.c
+++ b/cmd/usb_mass_storage.c
@@ -14,6 +14,7 @@
 #include <part.h>
 #include <usb.h>
 #include <usb_mass_storage.h>
+#include <watchdog.h>
 
 static int ums_read_sector(struct ums *ums_dev,
 			   ulong start, lbaint_t blkcnt, void *buf)
@@ -226,6 +227,8 @@
 			rc = CMD_RET_SUCCESS;
 			goto cleanup_register;
 		}
+
+		WATCHDOG_RESET();
 	}
 
 cleanup_register: