MAINTAINERS: update block/rbd.c maintainer

Jason has moved on from working on RBD and Ceph.  I'm taking over
his role upstream.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Message-Id: <20210519112513.19694-1-idryomov@gmail.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

MAINTAINERS

@@ -3060,7 +3060,7 @@ S: Supported
 F: block/vmdk.c
 
 RBD
-M: Jason Dillaman <dillaman@redhat.com>
+M: Ilya Dryomov <idryomov@gmail.com>
 L: qemu-block@nongnu.org
 S: Supported
 F: block/rbd.c