mb/google/volteer: Add new Audio option to FW_CONFIG

Volteer has a new Audio option in FW_CONFIG. This patch adds
support for it and when enabled, programs GPIO pins for I2S
functionality.

BUG=b:171174991
TEST=emerge-volteer coreboot

Change-Id: I85bc37980957a3fb6c795858a4e4f44f3e3cc332
Signed-off-by: Wisley Chen <wisley.chen@quantatw.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47291
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
diff --git a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
index 20a3843..50be736 100644
--- a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
@@ -15,6 +15,7 @@
 		option MAX98373_ALC5682I_I2S 2
 		option MAX98373_ALC5682_SNDW 3
 		option MAX98373_ALC5682I_I2S_UP4 4
+		option MAX98360_ALC5682I_I2S 5
 	end
 	field TABLETMODE 11
 		option TABLETMODE_DISABLED 0