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/plat/mediatek/mt6795/bl31.ld.S b/plat/mediatek/mt6795/bl31.ld.S
index b061b91..91ca87c 100644
--- a/plat/mediatek/mt6795/bl31.ld.S
+++ b/plat/mediatek/mt6795/bl31.ld.S
@@ -74,12 +74,7 @@
     ASSERT(. <= BL31_PROGBITS_LIMIT, "BL3-1 progbits has exceeded its limit.")
 #endif
 
-    stacks (NOLOAD) : {
-        __STACKS_START__ = .;
-        *(tzfw_normal_stacks)
-        __STACKS_END__ = .;
-    } >RAM
-
+    STACK_SECTION >RAM
     BSS_SECTION >RAM
     __RW_END__ = __BSS_END__;