wic: fix path parsing, use last occurrence

If the path contains 'scripts' more than once the first occurrence will be
incorrectly used. Use rfind instead of find to find the last occurrence.

(From OE-Core rev: f30c486c17060d2f21618612804a692512ad6a57)

Signed-off-by: George McCollister <george.mccollister@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/plugin.py

@@ -42,7 +42,7 @@ class PluginMgr():
 
     def __init__(self):
         wic_path = os.path.dirname(__file__)
-        eos = wic_path.find('scripts') + len('scripts')
+        eos = wic_path.rfind('scripts') + len('scripts')
         scripts_path = wic_path[:eos]
         self.scripts_path = scripts_path
         self.plugin_dir = scripts_path + PLUGIN_DIR