staging: lustre: lnet: dead code - remove LNetSetAsync

LNetSetAsync() returns 0, and is never called.  Doesn't exist in the Intel
tree, either.  Remove it.

Signed-off-by: Mike Shuey <shuey@purdue.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>