MAINTAINERS: Add more files to sam460ex

The sm501 model belonged to SH before but that seems to be inactive
now and latest changes were for sam460ex which is the more active user
of this device at the moment so let's adopt sm501 for sam460ex.

Also add device tree and firmware sources and binaries.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/MAINTAINERS b/MAINTAINERS
index 0bfd95a..fc0be06 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1052,8 +1052,14 @@
 M: BALATON Zoltan <balaton@eik.bme.hu>
 L: qemu-ppc@nongnu.org
 S: Maintained
+F: hw/ppc/sam460ex.c
+F: hw/ppc/ppc440_pcix.c
+F: hw/display/sm501*
 F: hw/ide/sii3112.c
 F: hw/timer/m41t80.c
+F: pc-bios/canyonlands.dt[sb]
+F: pc-bios/u-boot-sam460ex-20100605.bin
+F: roms/u-boot-sam460ex
 
 SH4 Machines
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