arm64: zynqmp: Enable SPL_CLK when SPL is enabled

Setup proper dependency in Kconfig for SPL_CLK.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7390995..f2c35e3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -773,7 +773,7 @@
 	select SUPPORT_SPL
 	select CLK
 	select SPL_BOARD_INIT if SPL
-	select SPL_CLK
+	select SPL_CLK if SPL
 	select DM_USB if USB
 	imply FAT_WRITE