CI: build: drop redundant generate ccache hash job

Drop redundant generare ccache hash job as that can be done by
integrated github expressions to generate an hash.
The only change is that the integrated way generate a sha256 hash
instead of an md5 sum.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

.github/workflows/build.yml

@@ -64,7 +64,6 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       owner_lc: ${{ steps.lower_owner.outputs.owner_lc }}
-      ccache_hash: ${{ steps.ccache_hash.outputs.ccache_hash }}
       container_tag: ${{ steps.determine_tools_container.outputs.container_tag }}
       container_name: ${{ steps.determine_tools_container.outputs.container_name }}
 
@@ -84,13 +83,6 @@ jobs:
 
           echo "owner_lc=$OWNER_LC" >> $GITHUB_OUTPUT
 
-      - name: Generate ccache hash
-        id: ccache_hash
-        run: |
-          CCACHE_HASH=$(md5sum include/kernel-* | awk '{ print $1 }' \
-           | md5sum | awk '{ print $1 }')
-          echo "ccache_hash=$CCACHE_HASH" >> $GITHUB_OUTPUT
-
       # Per branch tools container tag
       # By default stick to latest
       # For official test targetting openwrt stable branch
@@ -259,7 +251,7 @@ jobs:
         uses: actions/cache@v3
         with:
           path: openwrt/.ccache
-          key: ccache-kernel-${{ inputs.target }}/${{ inputs.subtarget }}-${{ needs.setup_build.outputs.ccache_hash }}
+          key: ccache-kernel-${{ inputs.target }}/${{ inputs.subtarget }}-${{ hashFiles('openwrt/include/kernel-**') }}
           restore-keys: |
             ccache-kernel-${{ inputs.target }}/${{ inputs.subtarget }}-