board: sifive: use ccache driver instead of helper function

Invokes the common cache_init function to initialize ccache.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/arch/riscv/cpu/fu540/Kconfig b/arch/riscv/cpu/fu540/Kconfig
index 05463b2..1604b41 100644
--- a/arch/riscv/cpu/fu540/Kconfig
+++ b/arch/riscv/cpu/fu540/Kconfig
@@ -19,6 +19,8 @@
 	imply SMP
 	imply CLK_SIFIVE
 	imply CLK_SIFIVE_PRCI
+	imply SIFIVE_CACHE
+	imply SIFIVE_CCACHE
 	imply SIFIVE_SERIAL
 	imply MACB
 	imply MII