libusbhost: Fix deadlock on devices without USB host support.

Change-Id: Ic91f99d1169fcdc00474dd6a870eb7e614128bc2
Signed-off-by: Mike Lockwood <lockwood@android.com>
diff --git a/libusbhost/usbhost.c b/libusbhost/usbhost.c
index f5ec140..06d91f5 100644
--- a/libusbhost/usbhost.c
+++ b/libusbhost/usbhost.c
@@ -162,6 +162,8 @@
     wds[0] = inotify_add_watch(context->fd, USB_FS_DIR, IN_CREATE | IN_DELETE);
     if (wds[0] < 0) {
         fprintf(stderr, "inotify_add_watch failed\n");
+        if (discovery_done_cb)
+            discovery_done_cb(client_data);
         return;
     }