MAINTAINERS: add rpmsg entry

People and scripts look for this.

Signed-off-by: Ohad Ben-Cohen <[e-mail]>

MAINTAINERS

···
 F:	Documentation/remoteproc.txt
 F:	include/linux/remoteproc.h
 
+REMOTE PROCESSOR MESSAGING (RPMSG) SUBSYSTEM
+M:	Ohad Ben-Cohen <[e-mail]>
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/ohad/rpmsg.git
+S:	Maintained
+F:	drivers/rpmsg/
+F:	Documentation/rpmsg.txt
+F:	include/linux/rpmsg.h
+
 RFKILL
 M:	Johannes Berg <[e-mail]>
 L:	[e-mail]