mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}()

Because DAMON debugfs interface and DAMON-based proactive reclaim are now
using monitoring operations via registration mechanism,
damon_{p,v}a_{target_valid,set_operations}() functions have no user.  This
commit clean them up.

Link: https://lkml.kernel.org/r/20220215184603.1479-9-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Xin Hao <xhao@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>