Clean up ARM mov 32bit immediate code in preparation for out of line constant pool.

R=rodolph.perfetta@arm.com, ulan@chromium.org

Review URL: https://codereview.chromium.org/138503002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19823 ce2b1a6d-e550-0410-aec6-3dcde31c8c00