sunxi: Enable CONFIG_SPL_STACK_R

Select CONFIG_SPL_STACK_R for sunxi boards, this gives us much more
room on the stack once we've the DRAM running.

Besides being a good change to have on itself, this also paves the
way for switching to using malloc_simple in the SPL which cuts of
close to 4KiB of the SPL size.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 55906b5..b336777 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -562,4 +562,8 @@
 	---help---
 	Set the GMAC Transmit Clock Delay Chain value.
 
+config SPL_STACK_R_ADDR
+	default 0x4fe00000 if MACH_SUN4I || MACH_SUN5I || MACH_SUN6I || MACH_SUN7I || MACH_SUN8I
+	default 0x2fe00000 if MACH_SUN9I
+
 endif