staging: lustre: remove ldebugfs_register_stats() wrapper function

staging: lustre: remove ldebugfs_register_stats() wrapper function

It was just calling debugfs_create_file() so unwind things and just call
the real function instead.  This ends up saving a number of lines as
there was never any error handling happening anyway, so that all can be
removed as well.

Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: James Simmons <jsimmons@infradead.org>
Cc: Ben Evans <bevans@cray.com>
Cc: Quentin Bouget <quentin.bouget@cea.fr>
Cc: NeilBrown <neilb@suse.com>
Cc: Arushi Singhal <arushisinghal19971997@gmail.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Patrick Farrell <paf@cray.com>
Cc: Aliaksei Karaliou <akaraliou.dev@gmail.com>
Cc: Aastha Gupta <aastha.gupta4104@gmail.com>
Cc: Dafna Hirschfeld <dafna3@gmail.com>
Cc: Mathias Rav <mathiasrav@gmail.com>
Cc: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Cc: Bob Glosman <bob.glossman@intel.com>
Cc: lustre-devel@lists.lustre.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>