b43: don't save dentries for debugfs

There is no need to keep around the dentry pointers for the debugfs
files as they will all be automatically removed when the subdir is
removed.  So save the space and logic involved in keeping them around by
just getting rid of them entirely.

By doing this change, we remove one of the last in-kernel user that was
storing the result of debugfs_create_bool(), so that api can be cleaned
up.

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Chao Yu <chao@kernel.org>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: b43-dev@lists.infradead.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210518163304.3702015-1-gregkh@linuxfoundation.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>