lockdep: save caller1 for locks in task_struct

Currently lockdep saves caller0 for locking API's in
task_struct. Save caller1 also for a task acquiring the
lock. This is helpful for locks like cpu_hotplug_lock
which is acquired/release inside a helper function like
cpus_read_lock(). Caller1 shall help in getting caller of
cpus_read_lock().

Change-Id: I3ea30990245f478778c2e58348a84ab40610056d
Signed-off-by: Prateek Sood <prsood@codeaurora.org>