MAINTAINERS: explicitly add Atmel SAMA5

Atmel SAMA5 SoCs are also supported through mach-at91.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

MAINTAINERS

@@ -911,7 +911,7 @@ M:	Tsahee Zidenberg <tsahee@annapurnalabs.com>
 S:	Maintained
 F:	arch/arm/mach-alpine/
 
-ARM/ATMEL AT91RM9200 AND AT91SAM ARM ARCHITECTURES
+ARM/ATMEL AT91RM9200, AT91SAM9 AND SAMA5 SOC SUPPORT
 M:	Nicolas Ferre <nicolas.ferre@atmel.com>
 M:	Alexandre Belloni <alexandre.belloni@free-electrons.com>
 M:	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>