kernel/arm: remove unneeded call to arch_thread_set_current_thread

Change-Id: I1026c733033458ed02fab9e9e61f041441e56d1e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6615
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

src/system/kernel/arch/arm/arch_cpu.cpp

@@ -21,10 +21,6 @@
 status_t
 arch_cpu_preboot_init_percpu(kernel_args *args, int curr_cpu)
 {
-	// The current thread must be NULL for all CPUs till we have threads.
-	// Some boot code relies on this.
-	arch_thread_set_current_thread(NULL);
-
 	return B_OK;
 }