Use --gc-sections during link

All common functions are being built into all binary images,
whether or not they are actually used. This change enables the
use of -ffunction-sections, -fdata-sections and --gc-sections
in the compiler and linker to remove unused code and data from
the images.

Change-Id: Ia9f78c01054ac4fa15d145af38b88a0d6fb7d409
diff --git a/bl2/bl2.ld.S b/bl2/bl2.ld.S
index 09dec75..edb676a 100644
--- a/bl2/bl2.ld.S
+++ b/bl2/bl2.ld.S
@@ -47,8 +47,8 @@
 
     ro . : {
         __RO_START__ = .;
-        *bl2_entrypoint.o(.text)
-        *(.text)
+        *bl2_entrypoint.o(.text*)
+        *(.text*)
         *(.rodata*)
         *(.vectors)
         __RO_END_UNALIGNED__ = .;
@@ -63,7 +63,7 @@
 
     .data . : {
         __DATA_START__ = .;
-        *(.data)
+        *(.data*)
         __DATA_END__ = .;
     } >RAM
 
@@ -79,7 +79,7 @@
      */
     .bss : ALIGN(16) {
         __BSS_START__ = .;
-        *(SORT_BY_ALIGNMENT(.bss))
+        *(SORT_BY_ALIGNMENT(.bss*))
         *(COMMON)
         __BSS_END__ = .;
     } >RAM