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/x86/kernel/process.c

@@ -121,8 +121,8 @@ static int set_new_tls(struct task_struct *p, unsigned long tls)
 		return do_set_thread_area_64(p, ARCH_SET_FS, tls);
 }
 
-int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
-		    unsigned long arg, struct task_struct *p, unsigned long tls)
+int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
+		struct task_struct *p, unsigned long tls)
 {
 	struct inactive_task_frame *frame;
 	struct fork_frame *fork_frame;

arch/x86/kernel/unwind_frame.c

@@ -269,7 +269,7 @@ bool unwind_next_frame(struct unwind_state *state)
 		/*
 		 * kthreads (other than the boot CPU's idle thread) have some
 		 * partial regs at the end of their stack which were placed
-		 * there by copy_thread_tls().  But the regs don't have any
+		 * there by copy_thread().  But the regs don't have any
 		 * useful information, so we can skip them.
 		 *
 		 * This user_mode() check is slightly broader than a PF_KTHREAD