pch_gbe: Fix build error by selecting all the possible dependencies.

Fengguang reported a kernel build failure as following:
drivers/built-in.o: In function `pch_gbe_ioctl':
pch_gbe_main.c:(.text+0x510370): undefined reference to `pch_ch_control_write'
pch_gbe_main.c:(.text+0x510393): undefined reference to `pch_ch_control_write'
pch_gbe_main.c:(.text+0x5103b3): undefined reference to `pch_ch_control_write'
...

It's a regression by commit da158646. The root cause is that
the CONFIG_PPS is not set there, consequently CONFIG_PTP_1588_CLOCK
can not be set anyway, which finally causes ptp_pch and pch_gbe_main
build failures.

As David prefers to use *select* to fix such module co-dependency issues,
this patch explicitly selects all the possible dependencies of PCH_PTP.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Reviewed-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NHaicheng Li <haicheng.lee@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/oki-semi/pch_gbe/Kconfig

@@ -26,6 +26,9 @@ if PCH_GBE
 config PCH_PTP
 	bool "PCH PTP clock support"
 	default n
+	depends on EXPERIMENTAL
+	select PPS
+	select PTP_1588_CLOCK
 	select PTP_1588_CLOCK_PCH
 	---help---
 	  Say Y here if you want to use Precision Time Protocol (PTP) in the