Add REFSPEC option for upgrade_mcp_release job

  * Branch should be possible to set like
    'build-with' parameter. Since in another case,
    default one will be always used from current version
    of mcp

Change-Id: Idbeb00d86cfe4c1303391893efe0f6c71590cbfd
Bug-related: PROD-22108 (PROD:22108)
1 file changed