bootconfig: Update MAINTAINERS file to add tree and mailing list

Since the bootconfig related changes will be handled on linux-trace
tree, add the tree and mailing lists for EXTRA BOOT CONFIG.

Link: https://lkml.kernel.org/r/167417138436.2333752.6988808113120359923.stgit@devnote3

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

MAINTAINERS

@@ -7894,7 +7894,11 @@ F:	include/linux/extcon/
 
 EXTRA BOOT CONFIG
 M:	Masami Hiramatsu <mhiramat@kernel.org>
+L:	linux-kernel@vger.kernel.org
+L:	linux-trace-kernel@vger.kernel.org
+Q:	https://patchwork.kernel.org/project/linux-trace-kernel/list/
 S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
 F:	Documentation/admin-guide/bootconfig.rst
 F:	fs/proc/bootconfig.c
 F:	include/linux/bootconfig.h