powerpc/perf/hv-24x7: Use kmem_cache_free

Free memory allocated using kmem_cache_zalloc using kmem_cache_free
rather than kfree.

The Coccinelle semantic patch that makes this change is as follows:

// <smpl>
@@
expression x,E,c;
@@

 x = \(kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\)(c,...)
 ... when != x = E
     when != &x
?-kfree(x)
+kmem_cache_free(c,x)
// </smpl>

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>