dlm: save master info after failed no-queue request

When a NOQUEUE request fails, the rsb res_master field is unnecessarily
reset to -1, instead of leaving the valid master setting in place.  We
want to save the looked-up master values while the rsb is on the "toss
list" so that another lookup can be avoided if the rsb is soon reused.
The fix is to simply leave res_master value alone.

Signed-off-by: David Teigland <teigland@redhat.com>