i3c: Resign from my maintainer role

I simply don't have time to maintain the I3C subsystem anymore.
Alexandre Belloni proposed to take over which I gladly accepted.
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/linux-i3c/20201125101643.461658-1-boris.brezillon@collabora.com

MAINTAINERS

@@ -8333,7 +8333,7 @@ F:	Documentation/devicetree/bindings/i3c/snps,dw-i3c-master.txt
 F:	drivers/i3c/master/dw*
 
 I3C SUBSYSTEM
-M:	Boris Brezillon <bbrezillon@kernel.org>
+M:	Alexandre Belloni <alexandre.belloni@bootlin.com>
 L:	linux-i3c@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 C:	irc://chat.freenode.net/linux-i3c