cpts: add missing kconfig dependency

The Common Platform Time Sync function of the CPSW does not depend the
CPSW configuration option as it should. This patch fixes the issue by
adding the dependency.
Signed-off-by: NRichard Cochran <richardcochran@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/Kconfig

@@ -62,6 +62,7 @@ config TI_CPSW
 
 config TI_CPTS
 	boolean "TI Common Platform Time Sync (CPTS) Support"
+	depends on TI_CPSW
 	select PTP_1588_CLOCK
 	---help---
 	  This driver supports the Common Platform Time Sync unit of