linker_script: move stacks section to bl_common.ld.h

The stacks section is the same for all BL linker scripts.

Move it to the common header file.

Change-Id: Ibd253488667ab4f69702d56ff9e9929376704f6c
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/bl2/bl2.ld.S b/bl2/bl2.ld.S
index 15df5dd..17475f0 100644
--- a/bl2/bl2.ld.S
+++ b/bl2/bl2.ld.S
@@ -88,12 +88,7 @@
         __DATA_END__ = .;
     } >RAM
 
-    stacks (NOLOAD) : {
-        __STACKS_START__ = .;
-        *(tzfw_normal_stacks)
-        __STACKS_END__ = .;
-    } >RAM
-
+    STACK_SECTION >RAM
     BSS_SECTION >RAM
     XLAT_TABLE_SECTION >RAM