netboot_firmware_settings.py: Prepend cwd to path

- Support running this tool from a symlink in factory

BUG=chromium:713599
TEST=ran platform/factory/setup/netboot_firmware_settings.py

Change-Id: Ie388d02e9144af850e447a6819af04107f52d6bf
Reviewed-on: https://chromium-review.googlesource.com/535059
Commit-Ready: Drew Davenport <ddavenport@chromium.org>
Tested-by: Drew Davenport <ddavenport@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
1 file changed