MAINTAINERS: add "C:" for URI for chat where developers hang out

Make it easier to find the developer chat for the subsystem or driver.

Link: http://lkml.kernel.org/r/1476966135-26943-3-git-send-email-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -76,6 +76,8 @@ Descriptions of section entries:
 	W: Web-page with status/info
 	B: URI for where to file bugs. A web-page with detailed bug
 	   filing info, a direct bug tracker link, or a mailto: URI.
+	C: URI for chat protocol, server and channel where developers
+	   usually hang out, for example irc://server/channel.
 	Q: Patchwork web based patch tracking system site
 	T: SCM tree type and location.
 	   Type is one of: git, hg, quilt, stgit, topgit