perf tools: Correct size given to memset

Memset should be given the size of the structure, not the size
of the pointer.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
type T;
T *x;
expression E;
@@

memset(x, E, sizeof(
+ *
 x))
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <Pine.LNX.4.64.0912092026000.1870@ask.diku.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>