mb/google/volteer/variant/copano: support regular/numpad touchpad

Define the 25th bit of the fw_config for the regular touchpad
and numpad touchpad selection.

BUG=b:174027837
BRANCH=firmware-volteer-13672.B
TEST=build pass

Change-Id: Ic5d61f19fd385600cfdcdd045dab1e61b06e4663
Signed-off-by: Zhuohao Lee <zhuohao@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50129
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Marco Chen <marcochen@google.com>
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 d74476a..ccde132 100644
--- a/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/volteer/variants/baseboard/devicetree.cb
@@ -58,6 +58,10 @@
 		option BOOT_SATA_DISABLED 0
 		option BOOT_SATA_ENABLED 1
 	end
+	field TOUCHPAD 25
+		option REGULAR_TOUCHPAD 0
+		option NUMPAD_TOUCHPAD 1
+	end
 end
 
 chip soc/intel/tigerlake