dm: drop CONFIG_DM_DEVICE_REMOVE from uncmd list

We do not want to compile the DM remove code for SPL.  Currently,
we undef it in include/config_uncmd_spl.h (for C files) and in
scripts/Makefile.uncmd_spl (for Makefiles).  This is really ugly.

This commit demonstrates how we can deprecate those two files.

Use $(SPL_) for the entry in the Makfile and CONFIG_IS_ENABLED()
in C files.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/Makefile b/drivers/core/Makefile
index ccc2fd4..1dd25a3 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -9,7 +9,7 @@
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_OF_CONTROL) += simple-bus.o
 endif
-obj-$(CONFIG_DM_DEVICE_REMOVE)	+= device-remove.o
+obj-$(CONFIG_$(SPL_)DM_DEVICE_REMOVE)	+= device-remove.o
 obj-$(CONFIG_DM)	+= dump.o
 obj-$(CONFIG_REGMAP)	+= regmap.o
 obj-$(CONFIG_SYSCON)	+= syscon-uclass.o