turnip: Fix file descriptor return.

Fix defect reported by Coverity Scan.

Logically dead code (DEADCODE)
dead_error_line: Execution cannot reach the expression -1 inside this statement: return ret ? -1 : handle.fd;

Fixes: cec0bc73e55 ("turnip: rework fences to use syncobjs")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7498>
(cherry picked from commit dad6b625768f2b68e1ea5c31da4e0e1415ef41bb)
2 files changed