Fix work-folder as parameter in build script.

[AndreRicardo-Zoetis]

Fix work-folder being created in default location even if --work-folder is passed.

Steps to reproduce:

$ rm -rf .workspace/
$ scripts/build.sh --work-folder /different_folder
Creating work folder: /workspaces/iot-hub-device-update/scripts/../.workspace

Notice how when passed --work-folder still created a folder in the default space rather than the passed parameter.

After this PR:

$ scripts/build.sh --work-folder /different_folder
Creating work folder: /different_folder