target/mips/mxu: Fix D16MAX D16MIN Q8MAX Q8MIN instructions

These instructions were designed that they overwrite source
register during partial storing of result.

Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Message-Id: <20230608104222.1520143-7-lis8215@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed