Blackfin: fix the section name of init_thread_union

Use the common attribute rather than setting the section name directly.
The common linker script defines expect the newer naming.

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/kernel/init_task.c b/arch/blackfin/kernel/init_task.c
index 118c5b9..d3970e8 100644
--- a/arch/blackfin/kernel/init_task.c
+++ b/arch/blackfin/kernel/init_task.c
@@ -28,5 +28,5 @@
  * "init_task" linker map entry.
  */
 union thread_union init_thread_union
-    __attribute__ ((__section__(".init_task.data"))) = {
+    __init_task_data = {
 INIT_THREAD_INFO(init_task)};