MAINTAINERS: Document virtex_ml507 machine

Place it in alphabetical order, there is a separate section for sharing
ppc4xx devices now.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Acked-by: NEdgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

MAINTAINERS

@@ -403,6 +403,12 @@ L: qemu-ppc@nongnu.org
 S: Supported
 F: hw/spapr*
 
+virtex_ml507
+M: Edgar E. Iglesias <edgar.iglesias@gmail.com>
+L: qemu-ppc@nongnu.org
+S: Odd Fixes
+F: hw/virtex_ml507.c
+
 SH4 Machines
 ------------
 R2D