tinymembench: not supported on MIPS n32/64 ABIs

This is a fix for 9883cbd3. After deeper
testing we have found that package is supported on MIPS64, but only for
o32 ABI.

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>