Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

Move the creation of debugfs files into a dedicated function, and ensure they are explicitly removed during vhci_release(), before associated data structures are freed.

Previously, debugfs files such as "force_suspend", "force_wakeup", and others were created under hdev->debugfs but not removed in vhci_release(). Since vhci_release() frees the backing vhci_data structure, any access to these files after release would result in use-after-free errors.

Although hdev->debugfs is later freed in hci_release_dev(), user can access files after vhci_data is freed but before hdev->debugfs is released.