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/sbc-pxs2.c b/arch/arm/mach-uniphier/sbc/sbc-pxs2.c
index 8c167ef..3275f22 100644
--- a/arch/arm/mach-uniphier/sbc/sbc-pxs2.c
+++ b/arch/arm/mach-uniphier/sbc/sbc-pxs2.c
@@ -10,6 +10,9 @@
 
 void uniphier_pxs2_sbc_init(void)
 {
+	if (!uniphier_sbc_is_enabled())
+		return;
+
 	uniphier_sbc_init_savepin();
 
 	/* necessary for ROM boot ?? */