microblaze: Setup correct pointer to TLS area

Setup a pointer to the TLS area in copy_thread.
r10 is 6th argumetn which contains TLS area.
And r21 is the thread reg.
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: David Holsgrove <david.holsgrove@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/process.c

@@ -182,8 +182,12 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 #endif
 	ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 
+	/*
+	 *  r21 is the thread reg, r10 is 6th arg to clone
+	 *  which contains TLS area
+	 */
 	if (clone_flags & CLONE_SETTLS)
-		;
+		childregs->r21 = childregs->r10;
 
 	return 0;
 }