staging: lustre: ldlm: remove unused field 'fwd_generation'

With this field gone, we don't need local variables 'imp' or 'obd'
any more.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>