MAINTAINERS: kgdb: Add myself as a reviewer for kgdb/kdb

I'm interested in kdb / kgdb and have sent various fixes over the
years.  I'd like to get CCed on patches so I can be aware of them and
also help review.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20190920104404.1.I237e68e8825e2d6ac26f8e847f521fe2fcc3705a@changeidSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -9075,6 +9075,7 @@ F:	security/keys/
 KGDB / KDB /debug_core
 M:	Jason Wessel <jason.wessel@windriver.com>
 M:	Daniel Thompson <daniel.thompson@linaro.org>
+R:	Douglas Anderson <dianders@chromium.org>
 W:	http://kgdb.wiki.kernel.org/
 L:	kgdb-bugreport@lists.sourceforge.net
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb.git