LiquidIO VF: s/select/imply/ for PTP_1588_CLOCK

Fix a minor fallout from the merge of the timers and the networking
trees. The following error may result if the PTP_1588_CLOCK
prerequisites are not available:

drivers/built-in.o: In function `ptp_clock_unregister':
(.text+0x40e0a5): undefined reference to `pps_unregister_source'
drivers/built-in.o: In function `ptp_clock_unregister':
(.text+0x40e0cc): undefined reference to `posix_clock_unregister'
drivers/built-in.o: In function `ptp_clock_event':
(.text+0x40e249): undefined reference to `pps_event'
drivers/built-in.o: In function `ptp_clock_register':
(.text+0x40e5e1): undefined reference to `pps_register_source'
drivers/built-in.o: In function `ptp_clock_register':
(.text+0x40e62c): undefined reference to `posix_clock_register'
drivers/built-in.o: In function `ptp_clock_register':
(.text+0x40e68d): undefined reference to `pps_unregister_source'
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/Kconfig

@@ -77,7 +77,7 @@ config OCTEON_MGMT_ETHERNET
 config LIQUIDIO_VF
 	tristate "Cavium LiquidIO VF support"
 	depends on 64BIT && PCI_MSI
-	select PTP_1588_CLOCK
+	imply PTP_1588_CLOCK
 	---help---
 	  This driver supports Cavium LiquidIO Intelligent Server Adapter
 	  based on CN23XX chips.