remove empty definition of display_boot_progress()

This patch replaces the empty definition of display_boot_progress() in
bl2_main.c with a weak definition. The former allowed bl2 to use the
early_exceptions(). It is possible to do that with a simple weak
definition as well.

Change-Id: Idb3f425a5e265f3579b638e3d26bd8c9bb78f80d

bl1/aarch64/early_exceptions.S

@@ -35,7 +35,7 @@
 #include <runtime_svc.h>
 
 	.globl	early_exceptions
-
+	.weak	display_boot_progress
 
 	.section	.text, "ax"; .align 11
 
@@ -214,3 +214,15 @@ SErrorA32:
 	mov	x0, #SERROR_AARCH32
 	bl	plat_report_exception
 	b	SErrorA32
+
+	.align	7
+	/* -----------------------------------------------------
+	 * BL1 redefines this function to print the fact that
+	 * BL2 has done its job and BL31 is about to be loaded.
+	 * This weak definition allows other bootloader stages
+	 * to use the 'early_exceptions' without running into
+	 * compilation errors.
+	 * -----------------------------------------------------
+	 */
+display_boot_progress:
+	ret

bl2/bl2_main.c

@@ -128,17 +128,3 @@ void bl2_main(void)
 	/* There is no valid reason for run_image() to return */
 	assert(0);
 }
-
-/*******************************************************************************
- * BL1 has this function to print the fact that BL2 has done its job and BL31 is
- * about to be loaded. Since BL2 re-uses BL1's exception table, it needs to
- * define this function as well.
- * TODO: Remove this function from BL2.
- ******************************************************************************/
-void display_boot_progress(unsigned long entrypoint,
-			   unsigned long spsr,
-			   unsigned long mem_layout,
-			   unsigned long ns_image_info)
-{
-	return;
-}