sparc: use .data.init_task section for init_thread_union

Use a dedicated aligned section for the init_thread_union
variable and declare this section in vmlinux.lds.

This align sparc with most other architectures.  Eventually this allow
the init_task bits to be unified across all architectures.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/init_task.c

@@ -23,6 +23,5 @@ EXPORT_SYMBOL(init_task);
  * in etrap.S which assumes it.
  */
 union thread_union init_thread_union
-	__attribute__((section (".text\"\n\t#")))
-	__attribute__((aligned (THREAD_SIZE)))
+	__attribute__((section (".data.init_task")))
 	= { INIT_THREAD_INFO(init_task) };