[arm] Shorter test names for parameterized tests.

See https://codereview.chromium.org/475823002 for the discussion.

TEST=compiler-unittests
R=jarin@chromium.org
BUG=v8:3489
LOG=n

Review URL: https://codereview.chromium.org/483643002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23142 ce2b1a6d-e550-0410-aec6-3dcde31c8c00