net: sched: Remove broken definitions and un-hide for !LOCKDEP

Currently, variables used only within lockdep expressions are flagged as
unused, requiring that these variables' declarations be decorated with
either #ifdef or __maybe_unused.  This results in ugly code.  This commit
therefore causes the full definitions of the lockdep_tcf_chain_is_locked()
and lockdep_tcf_proto_is_locked() functions to be visible even when
lockdep is not enabled, thus removing the need for the previous empty
functions that were provided in non-lockdep kernels.  This approach
further relies on dead-code elimination to remove any references to
functions or variables that are not available in non-lockdep kernels.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
--
CC: jhs@mojatatu.com
CC: xiyou.wangcong@gmail.com
CC: jiri@resnulli.us
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>