soc/intel/broadwell: Drop vboot support

There is an ongoing effort to deprecate VBOOT_VBNV_CMOS, and replace it
with VBOOT_VBNV_FLASH [1]. Since SOC_INTEL_BROADWELL doesn't support
flash writes in early stages (BOOT_DEVICE_SPI_FLASH_NO_EARLY_WRITES),
drop vboot as well as ChromeOS support for all broadwell boards,
including auron, jecht and wtm2.

[1] https://issuetracker.google.com/issues/235293589

BUG=b:235293589
TEST=./util/abuild/abuild -t GOOGLE_GUADO -a
TEST=./util/abuild/abuild -t GOOGLE_BUDDY -a

Change-Id: I002ab0f5f281c098afba16ada3621f1539c66d6b
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65782
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/soc/intel/broadwell/Kconfig

@@ -13,25 +13,6 @@ config SOC_SPECIFIC_OPTIONS
 	select MRC_SETTINGS_PROTECT
 	select REG_SCRIPT
 
-config BROADWELL_VBOOT_IN_BOOTBLOCK
-	depends on VBOOT
-	bool "Start verstage in bootblock"
-	default y
-	select VBOOT_STARTS_IN_BOOTBLOCK
-	help
-	  Broadwell can either start verstage in a separate stage
-	  right after the bootblock has run or it can start it
-	  after romstage for compatibility reasons.
-	  Broadwell however uses a mrc.bin to initialize memory which
-	  needs to be located at a fixed offset. Therefore even with
-	  a separate verstage starting after the bootblock that same
-	  binary is used meaning a jump is made from RW to the RO region
-	  and back to the RW region after the binary is done.
-
-config VBOOT
-	select VBOOT_MUST_REQUEST_DISPLAY
-	select VBOOT_STARTS_IN_ROMSTAGE if !BROADWELL_VBOOT_IN_BOOTBLOCK
-
 config ECAM_MMCONF_BASE_ADDRESS
 	default 0xf0000000
 
@@ -97,13 +78,6 @@ config MRC_BIN_ADDRESS
 	hex
 	default 0xfffa0000
 
-# The UEFI System Agent binary needs to be at a fixed offset in the flash
-# and can therefore only reside in the COREBOOT fmap region
-config RO_REGION_ONLY
-	string
-	depends on VBOOT
-	default "mrc.bin"
-
 endif # HAVE_MRC
 
 config HAVE_REFCODE_BLOB