cpu: at91: add driver for CPU

Add basic CPU driver use to retrieve information about CPU itself.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 85e5185..91b06b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -291,6 +291,7 @@
 T:	git https://gitlab.denx.de/u-boot/custodians/u-boot-atmel.git
 F:	arch/arm/mach-at91/
 F:	board/atmel/
+F:	drivers/cpu/at91_cpu.c
 F:	drivers/misc/microchip_flexcom.c
 F:	drivers/timer/mchp-pit64b-timer.c