arm: move exception handling out of start.S files

Exception handling is basically identical for all ARM targets.
Factorize it out of the various start.S files and into a
single vectors.S file, and adjust linker scripts accordingly.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
diff --git a/arch/arm/cpu/arm920t/ep93xx/u-boot.lds b/arch/arm/cpu/arm920t/ep93xx/u-boot.lds
index 9699404..623a635 100644
--- a/arch/arm/cpu/arm920t/ep93xx/u-boot.lds
+++ b/arch/arm/cpu/arm920t/ep93xx/u-boot.lds
@@ -16,7 +16,8 @@
 	.text      :
 	{
 		*(.__image_copy_start)
-	  arch/arm/cpu/arm920t/start.o	(.text*)
+		*(.vectors)
+		arch/arm/cpu/arm920t/start.o	(.text*)
 		/* the EP93xx expects to find the pattern 'CRUS' at 0x1000 */
 	  . = 0x1000;
 	  LONG(0x53555243)