Fix: f_count replaced with f_ref in Linux 6.13.0-rc1

Fix: f_count replaced with f_ref in Linux 6.13.0-rc1

See upstream commit 90ee6ed776c06435a3fe79c7f5344761f52e1760:

    commit 90ee6ed776c06435a3fe79c7f5344761f52e1760
    Author: Christian Brauner <brauner@kernel.org>
    Date:   Mon Oct 7 16:23:59 2024 +0200

        fs: port files to file_ref

        Port files to rely on file_ref reference to improve scaling and gain
        overflow protection.

        - We continue to WARN during get_file() in case a file that is already
          marked dead is revived as get_file() is only valid if the caller
          already holds a reference to the file. This hasn't changed just the
          check changes.

        - The semantics for epoll and ttm's dmabuf usage have changed. Both
          epoll and ttm synchronize with __fput() to prevent the underlying file
          from beeing freed.

Change-Id: I9f376af50835f15f74ff7fc82bdb752e09f77222
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>