arm: move C runtime setup code in crt0.S

Move all the C runtime setup code from every start.S
in arch/arm into arch/arm/lib/crt0.S. This covers
the code sequence from setting up the initial stack
to calling into board_init_r().

Also, rewrite the C runtime setup and make functions
board_init_*() and relocate_code() behave according to
normal C semantics (no jumping across the C stack any
more, etc).

Some SPL targets had to be touched because they use
start.S explicitly or for some reason; the relevant
maintainers and custodians are cc:ed.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 3422ac1..07baee2 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -36,6 +36,8 @@
 
 GLCOBJS	+= div0.o
 
+SOBJS-y += crt0.o
+
 ifndef CONFIG_SPL_BUILD
 COBJS-y	+= board.o
 COBJS-y	+= bootm.o