Log config file path

Added a log message to show the path of the configuration file being
used.
This improves visibility and helps users understand which config is
applied during flashing.

Signed-off-by: Mykhailo Androsiuk <mykhailo_androsiuk@epam.com>

Author: Mykhailo Androsiuk

rcar_flash/rcar_flash.py

@@ -88,6 +88,7 @@ def main():
         help='List of loaders to flash or "all" to flash all')
 
     args = parser.parse_args()
+    log.info(f"Using configuration file: {args.conf.name}")
 
     actions = {
         "list-loaders": do_list_loaders,