Kernel: Move wait_cycles() function to Aarch_asm_utils.S

Just a bit of housekeeping.

Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.S

@@ -1,12 +1,24 @@
 /*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
  * Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 .global get_current_exception_level
+.type get_current_exception_level, @function
 get_current_exception_level:
   mrs x0, CurrentEL
   lsr x0, x0, #2
   and x0, x0, #0x3
   ret
+
+.global wait_cycles
+.type wait_cycles, @function
+wait_cycles:
+Lstart:
+  // This is probably too fast when caching and branch prediction is turned on.
+  // FIXME: Make timer-based.
+  subs x0, x0, #1
+  bne Lstart
+  ret

Kernel/Prekernel/Arch/aarch64/Aarch64_asm_utils.h

@@ -7,3 +7,4 @@
 #pragma once
 
 extern "C" uint8_t get_current_exception_level();
+extern "C" void wait_cycles(int n);

Kernel/Prekernel/Arch/aarch64/boot.S

@@ -30,13 +30,3 @@ Lbss_clear_loop:
   bne Lbss_clear_loop
 
   b init
-
-.globl wait_cycles
-.type wait_cycles, @function
-wait_cycles:
-Lstart:
-  // This is probably too fast when caching and branch prediction is turned on.
-  // FIXME: Make timer-based.
-  subs x0, x0, #1
-  bne Lstart
-  ret