aarch32: add few missing weak platform specific function

Adds weak functions for plat_report_exception, bl1_plat_prepare_exit
and plat_error_handler in AArch32 mode.
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>

plat/common/aarch32/platform_helpers.S

@@ -7,16 +7,28 @@
 #include <arch.h>
 #include <asm_macros.S>
 
+	.weak	plat_report_exception
 	.weak	plat_crash_console_init
 	.weak	plat_crash_console_putc
 	.weak	plat_crash_console_flush
 	.weak	plat_reset_handler
 	.weak	plat_disable_acp
+	.weak	bl1_plat_prepare_exit
 	.weak	platform_mem_init
+	.weak	plat_error_handler
 	.weak	plat_panic_handler
 	.weak	bl2_plat_preload_setup
 	.weak	plat_try_next_boot_source
 
+	/* -----------------------------------------------------
+	 * Placeholder function which should be redefined by
+	 * each platform.
+	 * -----------------------------------------------------
+	 */
+func plat_report_exception
+	bx	lr
+endfunc plat_report_exception
+
 	/* -----------------------------------------------------
 	 * Placeholder function which should be redefined by
 	 * each platform.
@@ -73,6 +85,25 @@ func platform_mem_init
 	bx	lr
 endfunc platform_mem_init
 
+	/* -----------------------------------------------------
+	 * void bl1_plat_prepare_exit(entry_point_info_t *ep_info);
+	 * Called before exiting BL1. Default: do nothing
+	 * -----------------------------------------------------
+	 */
+func bl1_plat_prepare_exit
+	bx	lr
+endfunc bl1_plat_prepare_exit
+
+	/* -----------------------------------------------------
+	 * void plat_error_handler(int err) __dead2;
+	 * Endless loop by default.
+	 * -----------------------------------------------------
+	 */
+func plat_error_handler
+	wfi
+	b	plat_error_handler
+endfunc plat_error_handler
+
 	/* -----------------------------------------------------
 	 * void plat_panic_handler(void) __dead2;
 	 * Endless loop by default.