frontend/dri: fix bool/int comparison

Cast tex->bind & PIPE_BIND_PROTECTED to a bool before doing the
comparison, otherwise it'll incorrectly fail.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Fixes: 18b7cafc700 ("driconf: add disable_protected_content_check option")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11107>