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/lib/Makefile b/arch/arm/lib/Makefile
index e035d6a..585f1f7 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -11,7 +11,7 @@
 ifdef CONFIG_ARM64
 obj-y	+= crt0_64.o
 else
-obj-y	+= crt0.o
+obj-y	+= vectors.o crt0.o
 endif
 
 ifndef CONFIG_SPL_BUILD