bootmode: Get rid of CONFIG_BOOTMODE_STRAPS

With VBOOT_VERIFY_FIRMWARE separated from CHROMEOS, move recovery and
developer mode check functions to vboot. Thus, get rid of the
BOOTMODE_STRAPS option which controlled these functions under src/lib.

BUG=chrome-os-partner:55639

Change-Id: Ia2571026ce8976856add01095cc6be415d2be22e
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15868
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/vendorcode/google/chromeos/Kconfig

@@ -25,7 +25,6 @@ config CHROMEOS
 	select TPM2 if MAINBOARD_HAS_TPM2
 	select TPM_INIT_FAILURE_IS_FATAL if PC80_SYSTEM && LPC_TPM
 	select SKIP_TPM_STARTUP_ON_NORMAL_BOOT if PC80_SYSTEM && LPC_TPM
-	select BOOTMODE_STRAPS
 	select ELOG if SPI_FLASH
 	select COLLECT_TIMESTAMPS
 	select VBOOT