iwlegacy: 4965-rs: il4965_rs_alloc_sta: remove lq_sta local var

remove the lq_sta local variable and return the
result directly in il4965_rs_alloc_sta

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>