update selfhost runner logic

Author: sandeepgupta12

.github/workflows/_linux-build.yml

@@ -102,7 +102,7 @@ jobs:
     # Don't run on forked repos
 
     #runs-on: ["self-hosted", "Linux", "ppc64le"]
-    runs-on: ${{ fromJson(inputs.runner) }}
+    runs-on: ${{ inputs.runner_prefix}}${{ inputs.runner }}
 
     timeout-minutes: 240
     outputs:

.github/workflows/ppc64le.yml

@@ -39,4 +39,4 @@ jobs:
     with:
       build-environment: linux-ppc64le-binary-manywheel
       docker-image-name: pytorch-ppc64le:ubi9.3
-      runner: '["self-hosted", "Linux", "ppc64le"]'
+      runner: 'self-hosted,Linux,ppc64le'