r600/sfn: Fix usage of std::string constructor

Fixes: f718ac62688b (r600/sfn: Add a basic nir shader backend)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26415>
1 file changed