MAINTAINERS: update maintainers of chrome-platform

Add Tzung-Bi as a maintainer of chrome-platform.
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20230803100846.3223564-1-tzungbi@kernel.orgSigned-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

MAINTAINERS

@@ -4812,6 +4812,7 @@ F:	drivers/input/touchscreen/chipone_icn8505.c
 
 CHROME HARDWARE PLATFORM SUPPORT
 M:	Benson Leung <bleung@chromium.org>
+M:	Tzung-Bi Shih <tzungbi@kernel.org>
 L:	chrome-platform@lists.linux.dev
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git