staging: lustre: drop redundant check

There is no need to verify that its an error, as we are anyway going to
match the error value to -ENOENT.  Drop the redundant check.

Reported-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>