target/mips/mxu: Add S8STD S8LDI S8SDI instructions

These instructions are all load/store a byte from memory
and put it into/get it from MXU register in various combinations.
I-suffix instructions modify the base address GPR by offset provided.

Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Message-Id: <20230608104222.1520143-21-lis8215@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed