Bluetooth: vhci: Ignore return code of nonseekable_open()

The comment in ./fs/open.c clearly states that nonseekable_open() will
never fail. Therefore, we can safely ignore the return code. This is the
recommended way to deal with nonseekable_open().
Our current code looks like nonseekable_open() is checked for the return
code. However, if we check the return code, we must also kfree() our
private data if the open fails. To avoid this overhead and to avoid
confusion, we simply drop the return code and return 0.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>