Fix variable name for GKI_DEFCONFIG in build.yml

.github/workflows/build.yml

@@ -322,7 +322,7 @@ jobs:
           sed -i '/^config LSM$/,/^help$/{ /^[[:space:]]*default/ { /baseband_guard/! s/selinux/selinux,baseband_guard/ } }' security/Kconfig
 
           cd "$GITHUB_WORKSPACE"
-          sed -i '/^CONFIG_LSM=/ s/"$/,baseband_guard"/' "$DEFCONFIG"
+          sed -i '/^CONFIG_LSM=/ s/"$/,baseband_guard"/' "$GKI_DEFCONFIG"
 
       - name: Add unicodefix
         if: inputs.unicodefix == 'true'