CI: correctly output subtarget in label workflow

Commit bf8187d5dc ("CI: use split target and subtarget in label
workflow") didn't correctly output subtarget resulting in calling with
an empty subtarget. Fix this and correctly output generated subtarget.

Fixes: bf8187d5dc ("CI: use split target and subtarget in label workflow")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

.github/workflows/label-kernel.yml

@@ -13,6 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       target: ${{ steps.set_target.outputs.target }}
+      subtarget: ${{ steps.set_target.outputs.subtarget }}
 
     steps:
       - name: Set target

.github/workflows/label-target.yml

@@ -13,6 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       target: ${{ steps.set_target.outputs.target }}
+      subtarget: ${{ steps.set_target.outputs.subtarget }}
 
     steps:
       - name: Set target