arm: move image_copy_start/end to linker symbols

image_copy_start/end are defined as c variables in order to force the compiler
emit relative references. However, defining those within a section definition
will do the same thing since [0].

So let's remove the special sections from the linker scripts, the
variable definitions from sections.c and define them as a symbols within
a section.

[0] binutils commit 6b3b0ab89663 ("Make linker assigned symbol dynamic only for shared object")

Suggested-by: Sam Edwards <CFSworks@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Sam Edwards <CFSworks@gmail.com> # Binary output identical
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/arch/arm/mach-zynq/u-boot-spl.lds b/arch/arm/mach-zynq/u-boot-spl.lds
index 8c18d3f..d96a577 100644
--- a/arch/arm/mach-zynq/u-boot-spl.lds
+++ b/arch/arm/mach-zynq/u-boot-spl.lds
@@ -18,9 +18,9 @@
 SECTIONS
 {
 	. = ALIGN(4);
+	__image_copy_start = ADDR(.text);
 	.text :
 	{
-		__image_copy_start = .;
 		*(.vectors)
 		CPUDIR/start.o (.text*)
 		*(.text*)