ARM: uniphier: check DT to determine whether to initialize SBC

If CONFIG_MICRO_SUPPORT_CARD is enabled, U-Boot initialize SBC
(System Bus Controller), which may not be really necessary.

Check the "socionext,uniphier-system-bus" node in DT run-time.
If and only if it is found and its "status" property is okay,
initialize the SBC block.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/sbc/Makefile b/arch/arm/mach-uniphier/sbc/Makefile
index 912e05a..4efdd41 100644
--- a/arch/arm/mach-uniphier/sbc/Makefile
+++ b/arch/arm/mach-uniphier/sbc/Makefile
@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0+
 
+obj-					+= dummy.o
+
+ifndef CONFIG_SPL_BUILD
 obj-y					+= sbc.o
 
 obj-$(CONFIG_ARCH_UNIPHIER_LD4)		+= sbc-ld4.o
@@ -9,3 +12,4 @@
 obj-$(CONFIG_ARCH_UNIPHIER_LD11)	+= sbc-ld11.o
 obj-$(CONFIG_ARCH_UNIPHIER_LD20)	+= sbc-ld11.o
 obj-$(CONFIG_ARCH_UNIPHIER_PXS3)	+= sbc-pxs2.o
+endif