arm: fix incorrect monitor protection region in FLASH

Monitor protection region in FLASH did not cover .rel.dyn
and .dynsym sections, because it uses __bss_start to compute
monitor_flash_len. Use _end instead.

Add _end to linker scripts for end of u-boot image
Add _end_ofs to all the start.S.

Signed-off-by: Po-Yu Chuang <ratbert@faraday-tech.com>
diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
index c620d2c..dc46e21 100644
--- a/arch/arm/lib/board.c
+++ b/arch/arm/lib/board.c
@@ -459,7 +459,7 @@
 
 	gd->flags |= GD_FLG_RELOC;	/* tell others: relocation done */
 
-	monitor_flash_len = _bss_start_ofs;
+	monitor_flash_len = _end_ofs;
 	debug ("monitor flash len: %08lX\n", monitor_flash_len);
 	board_init();	/* Setup chipselects */