sunxi: Kconfig: Make SPL_FEL a toplevel Kconfig option

It's unfortunate that this needs to be present in both .config and spl/.config
since it makes it slightly hard to enable FEL mode for a regular defconfig. It
can be done with:
    echo CONFIG_SPL_FEL=y >> .config
    echo CONFIG_SPL_FEL=y >> spl/.config

Ideally only one of those would be needed.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index faa38ba..18f731a 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -42,6 +42,11 @@
 config SYS_SOC
 	default "sunxi"
 
+config SPL_FEL
+	bool "SPL/FEL mode support"
+	depends on SPL
+	default n
+
 config FDTFILE
 	string "Default fdtfile env setting for this board"