defconfig: sandbox: Enable SANDBOX_CLK_CCF to reuse generic CCF code

Enable by default the Common Clock Framework [CCF] clock code for sandbox.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 61391a7..f9c9b19 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -91,6 +91,7 @@
 CONFIG_DM_BOOTCOUNT=y
 CONFIG_DM_BOOTCOUNT_RTC=y
 CONFIG_CLK=y
+CONFIG_SANDBOX_CLK_CCF=y
 CONFIG_CPU=y
 CONFIG_DM_DEMO=y
 CONFIG_DM_DEMO_SIMPLE=y