list MST as pci layer maintainer

List MST as PCI maintainer so that people know
whom to Cc on patches.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

MAINTAINERS

diff --git a/MAINTAINERS b/MAINTAINERS
index 56f107e..9ebbb34 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -75,7 +75,7 @@
 TCG                       Fabrice Bellard
 IDE device                ?
 SCSI device               Paul Brook
-PCI layer                 ?
+PCI layer                 Michael S. Tsirkin
 USB layer                 ?
 Block layer               ?
 Graphic layer             ?