Fix the logging message to identify node by uuid

The logging message of _build_pxe_config method in
ironic/drivers/modules/pxe.py is like below:
Building PXE config for deployment 4.

"4" is a ID of the node, but users don't know ID of the node
even if using CLI or API.
Users can know only uuid of the node.
So that, uuid of the node should be written in the logging message.

This patch makes identify node by uuid not by id.

Change-Id: Ida220a97d5fc8f6c5adc5b5acf239bbee14ff847
Closes-bug: #1327085
Merge "Fix the logging message to identify node by uuid"