tests/tcg: target/mips: Remove an unnecessary file

Remove a file that was added long time ago by mistake. The commit
that introduced this file was commit d70080c4 (from 2012).

Reviewed-by: Aleksandar Rikalo <arikalo@wavecomp.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>