dump: Silence compiler warning in dump code when compiling with -Wshadow

Rename a variable to make this code compilable with -Wshadow.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20231004131338.215081-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-By: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Markus Armbruster <armbru@redhat.com>