mb/google/sarien: Enable EC _PTS/_WAK methods

Enable the option to have the system level _PTS/_WAK methods call
the EC provided methods when they are invoked by the OS.

Verified on sarien board by inspecting dsdt.dsl:

Method (_PTS, 1, NotSerialized)  // _PTS: Prepare To Sleep
{
    DBG0 = 0x96
    \_SB.PCI0.LPCB.EC0.PTS (Arg0)
}

Method (_WAK, 1, NotSerialized)  // _WAK: Wake
{
    DBG0 = 0x97
    \_SB.PCI0.LPCB.EC0.WAK (Arg0)
    Return (Package (0x02)
    {
        Zero,
        Zero
    })
}

Change-Id: I52be1c1cd7adae9ad317a51868735eb87a410549
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://review.coreboot.org/29614
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/sarien/Kconfig

@@ -15,6 +15,7 @@ config BOARD_GOOGLE_BASEBOARD_SARIEN
 	select MAINBOARD_HAS_TPM2
 	select SOC_INTEL_COFFEELAKE
 	select SOC_INTEL_CANNONLAKE_MEMCFG_INIT
+	select SOC_INTEL_COMMON_ACPI_EC_PTS_WAK
 	select SOC_INTEL_COMMON_BLOCK_SMM_ESPI_ACPI_DIS
 	select SPD_READ_BY_WORD
 	select SYSTEM_TYPE_LAPTOP