c6x: switch to copy_thread_tls()

Use the copy_thread_tls() calling convention which passes tls through a
register. This is required so we can remove the copy_thread{_tls}() split
and remove the HAVE_COPY_THREAD_TLS macro.

CC: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <jacquiot.aurelien@gmail.com>
Cc: linux-c6x-dev@linux-c6x.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

arch/c6x/Kconfig

@@ -22,6 +22,7 @@ config C6X
 	select GENERIC_CLOCKEVENTS
 	select MODULES_USE_ELF_RELA
 	select MMU_GATHER_NO_RANGE if MMU
+	select HAVE_COPY_THREAD_TLS
 
 config MMU
 	def_bool n

arch/c6x/kernel/process.c

@@ -104,9 +104,9 @@ void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
 /*
  * Copy a new thread context in its stack.
  */
-int copy_thread(unsigned long clone_flags, unsigned long usp,
-		unsigned long ustk_size,
-		struct task_struct *p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
+		    unsigned long ustk_size, struct task_struct *p,
+		    unsigned long tls)
 {
 	struct pt_regs *childregs;