lockdep: Clear whole lockdep_map on initialization

lockdep_init_map() only initializes parts of lockdep_map and triggers
kmemcheck warning when it is copied as a whole.  There isn't anything
to be gained by clearing selectively.  memset() the whole structure
and remove loop for ->class_cache[] clearing.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=35532

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Christian Casteyde <casteyde.christian@free.fr>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=35532
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110714131909.GJ3455@htj.dyndns.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>