MAINTAINERS: Mark linux-i3c mailing list moderated

The linux-i3c mailing list is moderated for non-subscribers.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

MAINTAINERS

@@ -7730,7 +7730,7 @@ F:	drivers/i2c/i2c-stub.c
 
 I3C SUBSYSTEM
 M:	Boris Brezillon <bbrezillon@kernel.org>
-L:	linux-i3c@lists.infradead.org
+L:	linux-i3c@lists.infradead.org (moderated for non-subscribers)
 C:	irc://chat.freenode.net/linux-i3c
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux.git
 S:	Maintained