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/drivers/cpu/Makefile b/drivers/cpu/Makefile
index 0b5dbc7..c853263 100644
--- a/drivers/cpu/Makefile
+++ b/drivers/cpu/Makefile
@@ -8,6 +8,7 @@
 
 obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
 obj-$(CONFIG_ARCH_IMX8) += imx8_cpu.o
+obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
 obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
 obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
 obj-$(CONFIG_SANDBOX) += cpu_sandbox.o