drivers/ptp/Kconfig: add "depends on HAS_IOMEM" for 'PTP_1588_CLOCK_PCH'

The related driver need depend on HAS_IOMEM, or may be built under UML architecture.

The related error (with allmodconfig, without pcap):

CC [M] drivers/ptp/ptp_pch.o
drivers/ptp/ptp_pch.c: In function ‘pch_remove’:
drivers/ptp/ptp_pch.c:571:3: error: implicit declaration of function ‘iounmap’ [-Werror=implicit-function-declaration] drivers/ptp/ptp_pch.c: In function ‘pch_probe’:
drivers/ptp/ptp_pch.c:621:2: error: implicit declaration of function ‘ioremap’ [-Werror=implicit-function-declaration] drivers/ptp/ptp_pch.c:621:13: warning: assignment makes pointer from integer without a cast [enabled by default]
cc1: some warnings being treated as errors

---
 drivers/ptp/Kconfig |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

index 5be73ba..5a7910e 100644
@@ -73,6 +73,7 @@ config DP83640_PHY
 config PTP_1588_CLOCK_PCH
 	tristate "Intel PCH EG20T as PTP clock"
 	depends on X86 || COMPILE_TEST
+	depends on HAS_IOMEM
 	select PTP_1588_CLOCK
 	help
 	  This driver adds support for using the PCH EG20T as a PTP

1.7.7.6