staging: unisys: Remove "struct dentry *eth_debugfs_dir"

staging: unisys: Remove "struct dentry *eth_debugfs_dir"

There is no need for "struct dentry *eth_debugfs_dir" which is used for
debug / sysfs directories. Therefore, remove this "struct dentry" and
everything related (i.e., creation and removal).

As a side effect of this change, the code has no more need of the
"cleanup_register_netdev" label, which can also be removed.

Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220331064751.29634-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>