bifrost: inventory: Downgrade log level to 'debug' for csv parsing
bifrost: inventory: Downgrade log level to 'debug' for csv parsing

Falling back to csv parsing is an intended behavior so downgrade the
log level to 'debug'. This also prevents the inventory script to print
the fallback message to stderr which can cause ansible-playbook to
fail to parse the rest of the output.

Change-Id: Ie79b70c9560ca627bc681948c9db3323ae9f447e

openstack/bifrost,openstack/bifrost