dm: core: Allow devres to be disabled in SPL

At present if devres is enabled in U-Boot proper it is enabled in SPL.
We don't normally want it there, so disable it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Angus Ainslie <angus@akkea.ca>
diff --git a/drivers/core/Makefile b/drivers/core/Makefile
index 3742e75..7099073 100644
--- a/drivers/core/Makefile
+++ b/drivers/core/Makefile
@@ -4,7 +4,7 @@
 
 obj-y	+= device.o fdtaddr.o lists.o root.o uclass.o util.o tag.o
 obj-$(CONFIG_$(SPL_TPL_)ACPIGEN) += acpi.o
-obj-$(CONFIG_DEVRES) += devres.o
+obj-$(CONFIG_$(SPL_TPL_)DEVRES) += devres.o
 obj-$(CONFIG_$(SPL_)DM_DEVICE_REMOVE)	+= device-remove.o
 obj-$(CONFIG_$(SPL_)SIMPLE_BUS)	+= simple-bus.o
 obj-$(CONFIG_SIMPLE_PM_BUS)	+= simple-pm-bus.o