lk: add build workflow

Signed-off-by: svoboda18 <dev.svoboda18@gmail.com>

.github/workflows/build.yml

@@ -0,0 +1,25 @@
+name: Build workflow
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  lk-build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout sources
+      uses: actions/checkout@v2
+    - name: Install pyhton2
+      run: sudo apt-get install python2
+    - name: Build the bootloader
+      run: |
+        export python=python2
+        make X5
+    - name : Upload bootloader
+      uses: actions/upload-artifact@v2
+      with:
+        name: X5_lk-signed.img
+        path: /home/runner/work/lk/lk/build-X5/lk-sign.img