mb/google/volteer: Add firmware configuration for MAX98373_ALC5682I_I2S_UP4

Add MAX98373_ALC5682I_I2S_UP4 firmware configuration option and configure GPIOs properly for UP4 design. The design is also for Halvor.

BUG=b:153680359, b:163382106
TEST=FW_NAME=halvor emerge-volteer coreboot chromeos-bootimage, fw_config value in Halvor:
> AUDIO=MAX98373_ALC5682I_I2S_UP4
ectool cbi set 6 0x00000400 4 2

Signed-off-by: Frank Wu <frank_wu@compal.corp-partner.google.com>
Change-Id: Ie25f278dfbdc2f41a36b70403699a2e3c2234600
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44560
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Caveh Jalali <caveh@chromium.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 7b018b2..3c1c5f0 100644
--- a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
@@ -13,6 +13,7 @@
 		option MAX98357_ALC5682I_I2S 1
 		option MAX98373_ALC5682I_I2S 2
 		option MAX98373_ALC5682_SNDW 3
+		option MAX98373_ALC5682I_I2S_UP4 4
 	end
 	field TABLETMODE 11
 		option TABLETMODE_DISABLED 0