MAINTAINERS: update Xen entries

moved in 56e2cd24..28b99f47 to hw/xen/ and hw/i386/xen/

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20170629150308.22766-4-f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -323,7 +323,6 @@ M: Stefano Stabellini <sstabellini@kernel.org>
 M: Anthony Perard <anthony.perard@citrix.com>
 L: xen-devel@lists.xenproject.org
 S: Supported
-F: xen-*
 F: */xen*
 F: hw/9pfs/xen-9p-backend.c
 F: hw/char/xen_console.c