update.py: ensure script can be run from any directory
update.py: ensure script can be run from any directory

Don't assume the current directory contains our conf/local.conf,
explicitly use the directory above where the script is located.

Signed-off-by: Paul Eggleton <737d4dae46a541673d7bf4e0d5b32714b16528d8@linux.intel.com>

bartosh/layerindex-web,bartosh/layerindex-web,bartosh/layerindex-web