skylake: Use COMMON_FADT

Remove the FADT from the individual mainboards and select and
use COMMON_FADT in the SOC instead.  Set the ACPI revision to 5.

Change-Id: Ieb87c467c71bc125f80c7d941486c2fbc9cd4020
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/17138
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
diff --git a/src/soc/intel/skylake/Kconfig b/src/soc/intel/skylake/Kconfig
index a5fb0e8..7591d66 100644
--- a/src/soc/intel/skylake/Kconfig
+++ b/src/soc/intel/skylake/Kconfig
@@ -19,6 +19,7 @@
 	select CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM if RELOCATABLE_RAMSTAGE
 	select C_ENVIRONMENT_BOOTBLOCK
 	select COLLECT_TIMESTAMPS
+	select COMMON_FADT
 	select CPU_INTEL_FIRMWARE_INTERFACE_TABLE
 	select GENERIC_GPIO_LIB
 	select HAVE_HARD_RESET