linkage.h: move from blackfin to common includes

1. Add linkage.h support from blackfin to common include,
   which is a reduced version from Linux.
2. Add architecture part support of linkage.h into blackfin
3. Fix include path of in blackfin related to linkage.h
   due to header file movement.

Signed-off-by: Macpaul Lin <macpaul@andestech.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/lib/outs.S b/arch/blackfin/lib/outs.S
index 253d4c3..39d5332 100644
--- a/arch/blackfin/lib/outs.S
+++ b/arch/blackfin/lib/outs.S
@@ -8,7 +8,7 @@
  * Licensed under the GPL-2.
  */
 
-#include <asm/linkage.h>
+#include <linux/linkage.h>
 
 .align 2