[IA64] perfmon: Change vmalloc to vzalloc and drop memset.

vzalloc() nicely zeroes memory for us, so we don't have to do a vmalloc()
and then manually memset() the returned memory when all we want is for it
to be zero. Patch changes this for pfm_rvmalloc().
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/perfmon.c

@@ -829,10 +829,9 @@ pfm_rvmalloc(unsigned long size)
 	unsigned long addr;
 
 	size = PAGE_ALIGN(size);
-	mem  = vmalloc(size);
+	mem  = vzalloc(size);
 	if (mem) {
 		//printk("perfmon: CPU%d pfm_rvmalloc(%ld)=%p\n", smp_processor_id(), size, mem);
-		memset(mem, 0, size);
 		addr = (unsigned long)mem;
 		while (size > 0) {
 			pfm_reserve_page(addr);