chromeos chipsets: select RTC usage

Since RTC is now a Kconfig ensure RTC is selected on the
x86 chipsets which are in Chrome OS devices. This allows
the eventlog to have proper timestamps instead of all
zeros.

BUG=chrome-os-partner:55993

Change-Id: I24ae7d9b3bf43a5791d4dc04aae018ce17fda72b
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16086
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/southbridge/intel/bd82x6x/Kconfig

@@ -37,6 +37,7 @@ config SOUTH_BRIDGE_OPTIONS # dummy
 	select ACPI_SATA_GENERATOR
 	select HAVE_INTEL_FIRMWARE
 	select SOUTHBRIDGE_INTEL_COMMON_GPIO
+	select RTC
 
 config EHCI_BAR
 	hex

src/southbridge/intel/lynxpoint/Kconfig

@@ -31,6 +31,7 @@ config SOUTH_BRIDGE_OPTIONS # dummy
 	select SPI_FLASH
 	select HAVE_INTEL_FIRMWARE
 	select HAVE_SPI_CONSOLE_SUPPORT
+	select RTC
 	select SOUTHBRIDGE_INTEL_COMMON_GPIO if !INTEL_LYNXPOINT_LP
 
 config INTEL_LYNXPOINT_LP