Update USB driver revision to 4.

Change-Id: I6cb6afa44bb69211d914f4a3237263fb02bdf617
diff --git a/sdk/usbdriver_source.properties b/sdk/usbdriver_source.properties
index d7666eb..3f9484b 100755
--- a/sdk/usbdriver_source.properties
+++ b/sdk/usbdriver_source.properties
@@ -1,4 +1,4 @@
-Pkg.Revision=3

+Pkg.Revision=4

 Archive.Os=WINDOWS

 Archive.Arch=ANY

 Extra.Path=usb_driver