fs: Improve eventpoll logging to stop indicting timerfd

fs: Improve eventpoll logging to stop indicting timerfd

timerfd doesn't create any wakelocks; eventpoll can, and is creating the
wakelocks we see called "[timerfd]".  eventpoll creates two kinds of
wakelocks: a single top-level lock associated with the eventpoll fd
itself, and one additional lock for each fd it is polling that needs such
a lock (e.g. those using EPOLLWAKEUP).  Current code names the per-fd
locks using the undecorated names of the fds' associated files (hence
"[timerfd]"), and is naming the top-level lock after the PID of the caller
and the name of the file behind the first fd for which a per-fd lock is
created.  To make things clearer, the top-level lock is now named using
the caller PID and an "epollfd" designation, while the per-fd locks are
also named with the caller's PID (to associate them with the top-level
lock) and their respective fds' file names.

Bug: 63622255
Bug: 38042165
Test: Ran on device and observed new wakelock naming in bugreport, dumpsys
batterystats, /d/tracing/trace, and d/wakeup_reasons.
Change-Id: I32bfe5fe6766bb569329a450cc7163d52d59ed34
Signed-off-by: Kelly Rossmoyer <krossmo@google.com>