check_whence: Add copy-firmware.sh to the list of ignored files

This was added recently as the script to install the firmware files.
Add it to the ignored list so check_whence doesn't complain about it.
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

check_whence.py

@@ -36,7 +36,7 @@ def main():
     whence_list = list(list_whence())
     known_files = set(name for name in whence_list if not name.endswith('/')) | \
                   set(['check_whence.py', 'configure', 'Makefile',
-                       'README', 'WHENCE'])
+                       'README', 'copy-firmware.sh', 'WHENCE'])
     known_prefixes = set(name for name in whence_list if name.endswith('/'))
     git_files = set(list_git())