vboot: Separate vboot from chromeos

VBOOT_VERIFY_FIRMWARE should be independent of CHROMEOS. This allows use
of verified boot library without having to stick to CHROMEOS.

BUG=chrome-os-partner:55639

Change-Id: Ia2c328712caedd230ab295b8a613e3c1ed1532d9
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15867
Tested-by: build bot (Jenkins)
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/lib/bootmode.c

@@ -22,7 +22,7 @@ int developer_mode_enabled(void)
 {
 	if (get_developer_mode_switch())
 		return 1;
-#if CONFIG_VBOOT_VERIFY_FIRMWARE
+#if CONFIG_VBOOT
 	if (vboot_handoff_check_developer_flag())
 		return 1;
 #endif