anv: fix minor gen_ioctl(I915_PERF_IOCTL_CONFIG) error handling issue

Found by Coverity.

Fixes: 2001a80d4a8 ("anv: Implement VK_KHR_performance_query")
Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6667>
1 file changed