tcl/target: Move nordic configuration files

tcl/target: Move nordic configuration files

Move target configuration files into a dedicated vendor directory as
required by the new guideline for configuration files.

Note that the moved files are still accessible via the old path to ensure
backwards compatibility. This works because of the extended file search in
vendor folders.

Change-Id: If3935985769dc543e8c7d72cda590c9d79303abb
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/8905
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins