io_uring: ensure fput() called correspondingly when direct install fails

io_fixed_fd_install() may fail for short of free fixed file bitmap,
in this case, need to call fput() correspondingly.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220527025400.51048-1-xiaoguang.wang@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>