Convert CONFIG_CLOCK_SYNTHESIZER to Kconfig

This converts the following to Kconfig:
   CONFIG_CLOCK_SYNTHESIZER

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am335x_evm_defconfig b/configs/am335x_evm_defconfig
index 497127d..fa97ec1 100644
--- a/configs/am335x_evm_defconfig
+++ b/configs/am335x_evm_defconfig
@@ -4,6 +4,7 @@
 CONFIG_TI_COMMON_CMD_OPTIONS=y
 CONFIG_DEFAULT_DEVICE_TREE="am335x-evm"
 CONFIG_AM33XX=y
+CONFIG_CLOCK_SYNTHESIZER=y
 CONFIG_AM335X_USB0=y
 CONFIG_AM335X_USB0_PERIPHERAL=y
 CONFIG_AM335X_USB1=y