target/nios2: Pass semihosting arg to exit

Instead of using R_ARG0 (the semihost function number), use R_ARG1
(the provided exit status).

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20230801152245.332749-1-keithp@keithp.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed