mb/google/rex/var/screebo: add hook for WiFi SAR table

As a preparation for WiFi SAR table addition, adding hook for it.

BUG=b:291155207
TEST=emerge-rex coreboot

Change-Id: Ia313cfddec278e6bf8498407b242c027a5891deb
Signed-off-by: YH Lin <yueherngl@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77598
Reviewed-by: Subrata Banik <subratabanik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/rex/Kconfig

@@ -64,6 +64,7 @@ config BOARD_GOOGLE_MODEL_REX_EC_ISH
 config BOARD_GOOGLE_MODEL_SCREEBO
 	def_bool n
 	select BOARD_GOOGLE_BASEBOARD_REX
+	select CHROMEOS_WIFI_SAR if CHROMEOS
 	select DRIVERS_GENERIC_ALC1015
 	select DRIVERS_GENESYSLOGIC_GL9750
 	select DRIVERS_GENESYSLOGIC_GL9750_INVERT_WP

src/mainboard/google/rex/variants/screebo/overridetree.cb

@@ -26,6 +26,10 @@ fw_config
 		option SD_GL9750		0
 		option SD_RTS5227S		1
 	end
+	field WIFI_SAR_ID 13
+		option WIFI_SAR_ID_0		0
+		option WIFI_SAR_ID_1		1
+	end
 end
 
 chip soc/intel/meteorlake

src/mainboard/google/rex/variants/screebo/variant.c

@@ -3,6 +3,12 @@
 #include <chip.h>
 #include <fw_config.h>
 #include <baseboard/variants.h>
+#include <sar.h>
+
+const char *get_wifi_sar_cbfs_filename(void)
+{
+	return get_wifi_sar_fw_config_filename(FW_CONFIG_FIELD(WIFI_SAR_ID));
+}
 
 void variant_update_soc_chip_config(struct soc_intel_meteorlake_config *config)
 {