MAINTAINERS: Update xen-devel mailing list address

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

MAINTAINERS

@@ -323,7 +323,7 @@ Guest CPU Cores (Xen):
 X86
 M: Stefano Stabellini <sstabellini@kernel.org>
 M: Anthony Perard <anthony.perard@citrix.com>
-L: xen-devel@lists.xensource.com
+L: xen-devel@lists.xenproject.org
 S: Supported
 F: xen-*
 F: */xen*