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

This change is only done where needed: some linker
scripts may contain relocation symbols yet remain
unchanged.

__rel_dyn_start and __rel_dyn_end each requires
its own output section; putting them in relocation
sections changes their flags and breaks relocation.

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/board/actux3/u-boot.lds b/board/actux3/u-boot.lds
index 9d43e95..5610644 100644
--- a/board/actux3/u-boot.lds
+++ b/board/actux3/u-boot.lds
@@ -68,10 +68,18 @@
 		*(.__image_copy_end)
 	}
 
+	.rel_dyn_start :
+	{
+		*(.__rel_dyn_start)
+	}
+
 	.rel.dyn : {
-		__rel_dyn_start = .;
 		*(.rel*)
-		__rel_dyn_end = .;
+	}
+
+	.rel_dyn_end :
+	{
+		*(.__rel_dyn_end)
 	}
 
 	_end = .;