MAINTAINERS: add Backlight subsystem co-maintainer

Add myself as co-maintainer for the backlight subsystem.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -1611,6 +1611,7 @@ F:	drivers/net/wireless/b43legacy/
 
 BACKLIGHT CLASS/SUBSYSTEM
 M:	Richard Purdie <rpurdie@rpsys.net>
+M:	Jingoo Han <jg1.han@samsung.com>
 S:	Maintained
 F:	drivers/video/backlight/
 F:	include/linux/backlight.h