of: clean up OF_CONTROL ifdef conditionals

We have flipped CONFIG_SPL_DISABLE_OF_CONTROL.  We have cleansing
devices, $(SPL_) and CONFIG_IS_ENABLED(), so we are ready to clear
away the ugly logic in include/fdtdec.h:

 #ifdef CONFIG_OF_CONTROL
 # if defined(CONFIG_SPL_BUILD) && !defined(SPL_OF_CONTROL)
 #  define OF_CONTROL 0
 # else
 #  define OF_CONTROL 1
 # endif
 #else
 # define OF_CONTROL 0
 #endif

Now CONFIG_IS_ENABLED(OF_CONTROL) is the substitute.  It refers to
CONFIG_OF_CONTROL for U-boot proper and CONFIG_SPL_OF_CONTROL for
SPL.

Also, we no longer have to cancel CONFIG_OF_CONTROL in
include/config_uncmd_spl.h and scripts/Makefile.spl.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/video/exynos_dp_lowlevel.c b/drivers/video/exynos_dp_lowlevel.c
index 05118f8..e9b461a 100644
--- a/drivers/video/exynos_dp_lowlevel.c
+++ b/drivers/video/exynos_dp_lowlevel.c
@@ -22,7 +22,7 @@
 
 void exynos_dp_set_base_addr(void)
 {
-#ifdef CONFIG_OF_CONTROL
+#if CONFIG_IS_ENABLED(OF_CONTROL)
 	unsigned int node = fdtdec_next_compatible(gd->fdt_blob,
 					0, COMPAT_SAMSUNG_EXYNOS5_DP);
 	if (node <= 0)