semihosting/uaccess: Briefly document returned values

Since it is not obvious the get/put_user*() methods
can return an error, add brief docstrings about it.
Also remind to use *unlock_user() when appropriate.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20241212115413.42109-1-philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250116160306.1709518-3-alex.bennee@linaro.org>
1 file changed