arm: make __image_copy_{start, end} compiler-generated

This change is only done where needed: some linker
scripts may contain __image_copy_{start,end} yet
remain unchanged.

Also, __image_copy_end needs its own section; putting
it in relocation sections changes their flags and makes
relocation break.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Tested-by: Lubomir Popov <lpopov@mm-sol.com>
Tested-by: Jeroen Hofstee <jeroen@myspectrum.nl>
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
index fe2ca98..d7adf90 100644
--- a/arch/arm/cpu/u-boot.lds
+++ b/arch/arm/cpu/u-boot.lds
@@ -33,7 +33,7 @@
 	. = ALIGN(4);
 	.text :
 	{
-		__image_copy_start = .;
+		*(.__image_copy_start)
 		CPUDIR/start.o (.text*)
 		*(.text*)
 	}
@@ -57,7 +57,10 @@
 
 	. = ALIGN(4);
 
-	__image_copy_end = .;
+	.image_copy_end :
+	{
+		*(.__image_copy_end)
+	}
 
 	.rel.dyn : {
 		__rel_dyn_start = .;