staging: usbip: userspace: add hwdata as optional dependency in README

This is an optional dependency since USB/IP can fully work without
it. However, it is needed to display device information such as
vendor.
Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/usbip/userspace/README

@@ -19,6 +19,10 @@
 
     - libtool, automake >= 1.9, autoconf >= 2.5.0, pkg-config
 
+[Optional]
+    - hwdata
+        Contains USB device identification data.
+
 
 [Install]
     0. Generate configuration scripts.