MAINTAINERS: Add entry for the include/hw/vfio/ folder

The headers in include/hw/vfio/ should be listed in the VFIO
section of the MAINTAINERS file.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index dc0aa54..5c4e23e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -866,6 +866,7 @@
 M: Alex Williamson <alex.williamson@redhat.com>
 S: Supported
 F: hw/vfio/*
+F: include/hw/vfio/
 
 vhost
 M: Michael S. Tsirkin <mst@redhat.com>