staging: lustre: replace kmalloc with kmalloc_array

This patch fixes the following checkpatch.pl warning:

WARNING: Prefer kmalloc_array over kmalloc with multiply
Signed-off-by: Denis Petrovic <denis.petrovic@edu.ece.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/libcfs/linux/linux-tracefile.c

@@ -57,8 +57,9 @@ int cfs_tracefile_init_arch(void)
 	memset(cfs_trace_data, 0, sizeof(cfs_trace_data));
 	for (i = 0; i < CFS_TCD_TYPE_MAX; i++) {
 		cfs_trace_data[i] =
-			kmalloc(sizeof(union cfs_trace_data_union) *
-				num_possible_cpus(), GFP_KERNEL);
+			kmalloc_array(num_possible_cpus(),
+				      sizeof(union cfs_trace_data_union),
+				      GFP_KERNEL);
 		if (!cfs_trace_data[i])
 			goto out;
 	}