Convert CONFIG_CLOCKS to Kconfig

This converts the following to Kconfig:
   CONFIG_CLOCKS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/xilinx_zynqmp_virt_defconfig b/configs/xilinx_zynqmp_virt_defconfig
index b43b90e..08c8008 100644
--- a/configs/xilinx_zynqmp_virt_defconfig
+++ b/configs/xilinx_zynqmp_virt_defconfig
@@ -30,6 +30,7 @@
 CONFIG_USE_PREBOOT=y
 CONFIG_PREBOOT="run scsi_init;usb start"
 CONFIG_BOARD_EARLY_INIT_R=y
+CONFIG_CLOCKS=y
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_FPGA=y
 CONFIG_SPL_OS_BOOT=y