Jenkinsfile: overide the KERNEL_URL and UBOOT_URL

Use the overides for the build step

Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>

Jenkinsfile

@@ -41,7 +41,7 @@ node {
           sh "make DIST='${params.dist}' BOARD='${params.board}' TYPE='${params.build_type}' check"
      }
      stage('Build') {
-          sh "make DIST='${params.dist}' BOARD='${params.board}' TYPE='${params.build_type}'"
+          sh "make DIST='${params.dist}' BOARD='${params.board}' TYPE='${params.build_type}' KERNEL_URL='${params.kernel_url}' UBOOT_URL='${params.uboot_url}'"
      }
      stage('Publish') {
           if( "${params.publish}"=="true" ) {