sparc: use struct_size() in kzalloc()

One of the more common cases of allocation size calculations is finding the
size of a structure that has a zero-sized array at the end, along with memory
for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now
use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/cpumap.c

@@ -194,8 +194,7 @@ static struct cpuinfo_tree *build_cpuinfo_tree(void)
 
 	n = enumerate_cpuinfo_nodes(tmp_level);
 
-	new_tree = kzalloc(sizeof(struct cpuinfo_tree) +
-	                   (sizeof(struct cpuinfo_node) * n), GFP_ATOMIC);
+	new_tree = kzalloc(struct_size(new_tree, nodes, n), GFP_ATOMIC);
 	if (!new_tree)
 		return NULL;