ARM64: Fix cctest/test-disasm-arm64/debug on real hardware.

Without the 'BREAK' parameter, no instruction is generated when we are not
running with the simulator.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/221903004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20443 ce2b1a6d-e550-0410-aec6-3dcde31c8c00