MAINTAINERS: Cover fuzzer reproducer tests within 'Device Fuzzing'

When we started to commit the fuzzer QTest reproducers to
fuzz-test.c in commit d8dd109 ("qtest: add fuzz test case"),
we forgot to add the corresponding MAINTAINERS entry. Do it now.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -2634,6 +2634,7 @@ R: Stefan Hajnoczi <stefanha@redhat.com>
 R: Thomas Huth <thuth@redhat.com>
 S: Maintained
 F: tests/qtest/fuzz/
+F: tests/qtest/fuzz-*test.c
 F: scripts/oss-fuzz/
 F: docs/devel/fuzzing.rst