checkpatch: fix check for the FSF address

checkpatch: fix check for the FSF address

Commit 4525c0a4c4d0aaa199c37a6d2245617e8445f213 cherry-picked check
for the FSF address presence from upstream. However, it has a typo
resulting in this obscure error when triggered:

Use of uninitialized value in concatenation (.) or string at /home/jenkins/.jenkins/jobs/openocd-gerrit/workspace/tools/scripts/checkpatch.pl line 1258.
ERROR:

This patch fixes it.

Change-Id: Ia417ef4782d21c8b3f1d39de88c4ab850a5a6630
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2414
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>