Fix pkgconfig to avoid lintian warning.
--- a/libusb3380.pc.in
+++ b/libusb3380.pc.in
@@ -10,6 +10,3 @@
 Requires: libusb
 Conflicts:
 Cflags: -I${includedir}
-Libs: -L${libdir} -lusb-1.0
-Libs.private:  -lusb-1.0
-