fs: dlm: remove deprecated code parts

This patch removes code parts which was declared deprecated by
commit 6b0afc0c ("fs: dlm: don't use deprecated timeout features by
default"). This contains the following dlm functionality:

- start a cancel of a dlm request did not complete after certain timeout:
  The current way how dlm cancellation works and interfering with other
  dlm requests triggered by the user can end in an overlapping and
  returning in -EBUSY. The most user don't handle this case and are
  unaware that DLM can return such errno in such situation. Due the
  timeout the user are mostly unaware when this happens.
- start a netlink warning messages for user space if dlm requests did
  not complete after certain timeout:
  This feature was never being built in the only known dlm user space side.
  As we are to remove the timeout cancellation feature we can directly
  remove this feature as well.

There might be the possibility to bring the timeout cancellation feature
back. However the current way of handling the -EBUSY case which is only
a software limitation and not a hardware limitation should be changed.
We minimize the current code base in DLM cancellation feature to not have
to deal with those existing features while solving the DLM cancellation
feature in general.

UAPI define DLM_LSFL_TIMEWARN is commented as deprecated and reserved
value. We should avoid at first to give it a new meaning but let
possible users still compile by keeping this define. In far future we
can give this flag a new meaning. The same for the DLM_LKF_TIMEOUT lock
request flag.

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