ac: Don't negate strstr return values in ac_query_gpu_info

ac: Don't negate strstr return values in ac_query_gpu_info

strstr returns a pointer to the needle sub-string within the haystack
string if the latter contains the former, or NULL otherwise. So this
essentially always set info->is_pro_graphics = true, since probably no
marketing name ever contains all of these sub-strings.

Fixes: b635dff25620 "ac: fix detection of Pro graphics"
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7675>