vendor/download: check whether configs exist first

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/vendor/download

@@ -42,6 +42,12 @@ main()
 
 detect_firmware()
 {
+	_cfg_exists="n"
+	for _chk_file in "${boarddir}/config/"*; do
+		[ -f "${_chk_file}" ] && _cfg_exists="y" && break
+	done
+	[ "${_cfg_exists}" = "n" ] && return 1
+
 	set -- "${boarddir}/config/"*
 	. "${1}" 2>/dev/null