Read the arm64 midr register earlier

We use the midr_el1 register to decode which CPU type we are booting
from. Read it on the secondary CPUs before waiting for the boot CPU
to release us as it will need to use it before the release.

Sponsored by:	The FreeBSD Foundation

sys/arm64/arm64/mp_machdep.c

@@ -238,6 +238,7 @@ init_secondary(uint64_t cpu)
 	 * We need this before signalling the CPU is ready to
 	 * let the boot CPU use the results.
 	 */
+	pcpup->pc_midr = get_midr();
 	identify_cpu(cpu);
 
 	/* Ensure the stores in identify_cpu have completed */
@@ -248,8 +249,6 @@ init_secondary(uint64_t cpu)
 	while (!atomic_load_int(&aps_ready))
 		__asm __volatile("wfe");
 
-	pcpup->pc_midr = get_midr();
-
 	/* Initialize curthread */
 	KASSERT(PCPU_GET(idlethread) != NULL, ("no idle thread"));
 	pcpup->pc_curthread = pcpup->pc_idlethread;