cros_config: Use `cros_config / name` instead of mosys

BUG=b:153270707
TEST=test the code snippet on dut to make sure it works

Cq-Depend: chromium:2505235
Change-Id: I4229ad2ce9bf7384baa5917c30af8b18a9d47be6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/factory_installer/+/2503756
Reviewed-by: Cheng-Han Yang <chenghan@chromium.org>
Commit-Queue: Yilin Yang (kerker) <kerker@chromium.org>
Tested-by: Yilin Yang (kerker) <kerker@chromium.org>
diff --git a/factory_cros_payload.sh b/factory_cros_payload.sh
index 81fcabb..895229f 100644
--- a/factory_cros_payload.sh
+++ b/factory_cros_payload.sh
@@ -12,7 +12,12 @@
 cros_payload_metadata() {
   local src_media="$1"
   local payloads_dir="$(cros_payload get_cros_payloads_dir)"
-  local model="$(mosys platform model)"
+
+  local model="$(cros_config / name)"
+  if [ -z "${model}" ]; then
+    model="$(mosys platform model)"
+  fi
+
   local model_json_path="${payloads_dir}/${model}.json"
   local board="$(findLSBValue CHROMEOS_RELEASE_BOARD)"
   local board_json_path="${payloads_dir}/${board}.json"