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/board/freescale/mx31ads/u-boot.lds b/board/freescale/mx31ads/u-boot.lds
index 6da1d4b..61b83bf 100644
--- a/board/freescale/mx31ads/u-boot.lds
+++ b/board/freescale/mx31ads/u-boot.lds
@@ -22,6 +22,7 @@
 	  /* WARNING - the following is hand-optimized to fit within	*/
 	  /* the sector layout of our flash chips!	XXX FIXME XXX	*/
 
+	  *					(.vectors)
 	  arch/arm/cpu/arm1136/start.o		(.text*)
 	  board/freescale/mx31ads/built-in.o	(.text*)
 	  arch/arm/lib/built-in.o		(.text*)