mb/google/brox/var/lotso: Add FW_CONFIG for FP

This patch adds FW_CONFIG to accommodate different Lotso BoM
components across various SKUs.
1. Fingerprint sensor - FP Present/Absent

BUG=b:350360162
BRANCH=None
TEST=Boot image on SKU2 and check FP working.

Change-Id: I1ee5fcd1c29099bdbee741ef76c00cf45fcc1189
Signed-off-by: Wentao Qin <qinwentao@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83388
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/brox/variants/lotso/overridetree.cb

@@ -26,6 +26,10 @@ fw_config
 		option KB_BL_ABSENT		0
 		option KB_BL_PRESENT		1
 	end
+	field FP 11 12
+		option FP_PRESENT		0
+		option FP_ABSENT		1
+	end
 	field ISH 21
 		option ISH_DISABLE		0
 		option ISH_ENABLE		1