staging: lustre: no need to check debugfs return values

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Clean up the lustre core code by not caring about the value of debugfs
calls.  This ends up removing a number of lines of code that are not
needed.

Note, more work is needed to remove the unneeded debugfs wrapper
functions in the future.

Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: James Simmons <jsimmons@infradead.org>
Cc: NeilBrown <neilb@suse.com>
Cc: Ben Evans <bevans@cray.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: "John L. Hammond" <john.hammond@intel.com>
Cc: Dafna Hirschfeld <dafna3@gmail.com>
Cc: Mathias Rav <mathiasrav@gmail.com>
Cc: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Cc: lustre-devel@lists.lustre.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>