nightly-kernel.conf: add arm64 build
nightly-kernel.conf: add arm64 build

arm64 is far enough along that we should be trying to build it.

Signed-off-by: Beth Flanagan <86e3219095765dcc0f6f42aef4bd43803a05b796@intel.com>

denny820909/builder,denny820909/builder,denny820909/builder,denny820909/builder