Remove unused color declarations in the a64 simulator

They're now all defined globally

BUG=none
R=svenpanne@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/207723003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20144 ce2b1a6d-e550-0410-aec6-3dcde31c8c00