Make BL1 RO and RW base addresses configurable

BL1 RO and RW base address used to be fixed, respectively to the first
address of the Trusted ROM and the first address of the Trusted RAM.

Introduce new platform defines to configure the BL1 RO and RW base
addresses.

Change-Id: If26616513a47798593a4bb845a4b0fb37c867cd6
diff --git a/bl1/bl1.ld.S b/bl1/bl1.ld.S
index 81c5443..11b9a8f 100644
--- a/bl1/bl1.ld.S
+++ b/bl1/bl1.ld.S
@@ -41,7 +41,11 @@
 
 SECTIONS
 {
-    ro : {
+    . = BL1_RO_BASE;
+    ASSERT(. == ALIGN(4096),
+           "BL1_RO_BASE address is not aligned on a page boundary.")
+
+    ro . : {
         __RO_START__ = .;
         *bl1_entrypoint.o(.text*)
         *(.text*)
@@ -52,16 +56,19 @@
 
     /*
      * The .data section gets copied from ROM to RAM at runtime.
-     * Its LMA and VMA must be 16-byte aligned.
+     * Its LMA must be 16-byte aligned.
+     * Its VMA must be page-aligned as it marks the first read/write page.
      */
-    . = NEXT(16);        /* Align LMA */
-    .data : ALIGN(16) {  /* Align VMA */
+    . = BL1_RW_BASE;
+    ASSERT(. == ALIGN(4096),
+           "BL1_RW_BASE address is not aligned on a page boundary.")
+    .data . : ALIGN(16) {
         __DATA_RAM_START__ = .;
         *(.data*)
         __DATA_RAM_END__ = .;
     } >RAM AT>ROM
 
-    stacks (NOLOAD) : {
+    stacks . (NOLOAD) : {
         __STACKS_START__ = .;
         *(tzfw_normal_stacks)
         __STACKS_END__ = .;