remove workflow file from micropython

.github/workflows/ports_mimxrt.yml

@@ -1,23 +0,0 @@
-name: mimxrt port
-
-on:
-  push:
-  pull_request:
-    paths:
-      - '.github/workflows/*.yml'
-      - 'tools/**'
-      - 'py/**'
-      - 'extmod/**'
-      - 'lib/**'
-      - 'drivers/**'
-      - 'ports/mimxrt/**'
-
-jobs:
-  build:
-    runs-on: ubuntu-20.04
-    steps:
-    - uses: actions/checkout@v2
-    - name: Install packages
-      run: source tools/ci.sh && ci_mimxrt_setup
-    - name: Build
-      run: source tools/ci.sh && ci_mimxrt_build