ARM: uniphier: revive accidentally removed dcache_disable()

Commit a8e6300d483d ("ARM: uniphier: refactor spl_init_board()")
accidentally dropped dcache_disable() call.  Since then, the SPL of
LD11 and LD20 failed to load U-Boot proper.

Fixes: a8e6300d483d ("ARM: uniphier: refactor spl_init_board()")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/spl_board_init.c b/arch/arm/mach-uniphier/spl_board_init.c
index da749a3..0079a08 100644
--- a/arch/arm/mach-uniphier/spl_board_init.c
+++ b/arch/arm/mach-uniphier/spl_board_init.c
@@ -168,4 +168,8 @@
 		pr_err("failed to init DRAM\n");
 		hang();
 	}
+
+#ifdef CONFIG_ARM64
+	dcache_disable();
+#endif
 }