arch: rename copy_thread_tls() back to copy_thread()

Now that HAVE_COPY_THREAD_TLS has been removed, rename copy_thread_tls()
back simply copy_thread(). It's a simpler name, and doesn't imply that only
tls is copied here. This finishes an outstanding chunk of internal process
creation work since we've added clone3().

Cc: linux-arch@vger.kernel.org
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>A
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Greentime Hu <green.hu@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>A
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

arch/ia64/kernel/process.c

@@ -311,7 +311,7 @@ ia64_load_extra (struct task_struct *task)
  *	<clone syscall>	        <some kernel call frames>
  *	sys_clone		   :
  *	_do_fork		_do_fork
- *	copy_thread_tls		copy_thread_tls
+ *	copy_thread		copy_thread
  *
  * This means that the stack layout is as follows:
  *
@@ -333,9 +333,8 @@ ia64_load_extra (struct task_struct *task)
  * so there is nothing to worry about.
  */
 int
-copy_thread_tls(unsigned long clone_flags, unsigned long user_stack_base,
-		    unsigned long user_stack_size, struct task_struct *p,
-		    unsigned long tls)
+copy_thread(unsigned long clone_flags, unsigned long user_stack_base,
+	    unsigned long user_stack_size, struct task_struct *p, unsigned long tls)
 {
 	extern char ia64_ret_from_clone;
 	struct switch_stack *child_stack, *stack;