drivers/wifi, mb/google: Drop config WIFI_SAR_CBFS

Now that SAR support in VPD is deprecated in coreboot, there is no
need for a separate Kconfig `WIFI_SAR_CBFS` as the SAR table is only
supported as a CBFS file. This change drops the config `WIFI_SAR_CBFS`
from drivers/wifi/generic/Kconfig and its selection in
mb/google/.../Kconfig.

wifi_sar_defaults.hex is added to CBFS only if
CONFIG_WIFI_SAR_CBFS_FILEPATH is not empty because current mainboards
do not provide a default SAR file in
coreboot. Thus, CONFIG_WIFI_SAR_CBFS_FILEPATH is updated to have a
default value of "".

BUG=b:173465272

Cq-Depend: chromium:2757781
Change-Id: I0bb8f6e2511596e4503fe4d8c34439228ceaa3c7
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51484
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

src/drivers/wifi/generic/Kconfig

@@ -21,9 +21,6 @@ config USE_SAR
 	default n
 	help
 	  Enable it when wifi driver uses SAR configuration feature.
-	  VPD entry "wifi_sar" is read to get SAR settings, if its
-	  not found driver may look into CBFS for default settigs.
-	  WIFI_SAR_CBFS is option to enable CBFS lookup.
 
 config SAR_ENABLE
 	bool
@@ -40,20 +37,10 @@ config GEO_SAR_ENABLE
 	default n
 	depends on USE_SAR
 
-config WIFI_SAR_CBFS
-	bool "Enable SAR table addition to CBFS"
-	default n
-	depends on USE_SAR
-	help
-	 wifi driver would look for "wifi_sar" vpd key and load SAR settings from
-	 it, if the vpd key is not found then the driver tries to look for sar
-	 settings from CBFS with file name wifi_sar_defaults.hex.
-	 So OEM/ODM can override wifi sar with VPD.
-
 config WIFI_SAR_CBFS_FILEPATH
 	string "The cbfs file which has WIFI SAR defaults"
-	depends on WIFI_SAR_CBFS
+	depends on USE_SAR
-	default "src/mainboard/\$(MAINBOARDDIR)/wifi_sar_defaults.hex"
+	default ""
 
 config DSAR_SET_NUM
 	hex "Number of SAR sets when D-SAR is enabled"

src/drivers/wifi/generic/Makefile.inc

@@ -5,8 +5,14 @@ ramstage-y += generic.c
 ramstage-$(CONFIG_GENERATE_SMBIOS_TABLES) += smbios.c
 ramstage-$(CONFIG_HAVE_ACPI_TABLES) += acpi.c
 
-cbfs-files-$(CONFIG_WIFI_SAR_CBFS)  += wifi_sar_defaults.hex
+CONFIG_WIFI_SAR_CBFS_FILEPATH := $(call strip_quotes,$(CONFIG_WIFI_SAR_CBFS_FILEPATH))
-wifi_sar_defaults.hex-file := $(call strip_quotes,$(CONFIG_WIFI_SAR_CBFS_FILEPATH))
+
+ifneq ($(CONFIG_WIFI_SAR_CBFS_FILEPATH),)
+
+cbfs-files-$(CONFIG_USE_SAR) += wifi_sar_defaults.hex
+wifi_sar_defaults.hex-file := $(CONFIG_WIFI_SAR_CBFS_FILEPATH)
 wifi_sar_defaults.hex-type := raw
 
 endif
+
+endif

src/mainboard/google/dedede/Kconfig

@@ -55,7 +55,6 @@ config CHROMEOS_WIFI_SAR
 	select DSAR_ENABLE
 	select SAR_ENABLE
 	select USE_SAR
-	select WIFI_SAR_CBFS
 
 config DEVICETREE
 	string

src/mainboard/google/drallion/Kconfig

@@ -40,7 +40,6 @@ config CHROMEOS_WIFI_SAR
 	select GEO_SAR_ENABLE
 	select SAR_ENABLE
 	select USE_SAR
-	select WIFI_SAR_CBFS
 
 config DIMM_MAX
 	int

src/mainboard/google/hatch/Kconfig

@@ -62,7 +62,6 @@ config CHROMEOS_WIFI_SAR
 	select GEO_SAR_ENABLE
 	select SAR_ENABLE
 	select USE_SAR
-	select WIFI_SAR_CBFS
 
 config DEVICETREE
 	string

src/mainboard/google/volteer/Kconfig

@@ -56,7 +56,6 @@ config CHROMEOS_WIFI_SAR
 	select GEO_SAR_ENABLE
 	select SAR_ENABLE
 	select USE_SAR
-	select WIFI_SAR_CBFS
 
 config DIMM_SPD_SIZE
 	int