Teach the arm64 kernel to identify the Arm AEM

The Arm Architecture Envelope Model is a simulator that models the
architecture rather than any specific implementation. Add its part ID
macro and add it to the list of Arm CPUs we can decode.

Sponsored by:	The FreeBSD Foundation

sys/arm64/arm64/identcpu.c

@@ -190,6 +190,7 @@ struct cpu_implementers {
  */
 /* ARM Ltd. */
 static const struct cpu_parts cpu_parts_arm[] = {
+	{ CPU_PART_AEM_V8, "AEMv8" },
 	{ CPU_PART_FOUNDATION, "Foundation-Model" },
 	{ CPU_PART_CORTEX_A35, "Cortex-A35" },
 	{ CPU_PART_CORTEX_A53, "Cortex-A53" },

sys/arm64/include/cpu.h

@@ -93,6 +93,7 @@
 #define	CPU_PART_NEOVERSE_N1	0xD0C
 #define	CPU_PART_CORTEX_A77	0xD0D
 #define	CPU_PART_CORTEX_A76AE	0xD0E
+#define	CPU_PART_AEM_V8		0xD0F
 
 /* Cavium Part numbers */
 #define	CPU_PART_THUNDERX	0x0A1