bnx2x: 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;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, 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)

Notice that, in this case, variable fsz is not necessary, hence
it is removed.

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>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c

@@ -1654,13 +1654,9 @@ static int bnx2x_vf_mbx_macvlan_list(struct bnx2x *bp,
 {
 	int i, j;
 	struct bnx2x_vf_mac_vlan_filters *fl = NULL;
-	size_t fsz;
 
-	fsz = tlv->n_mac_vlan_filters *
-	      sizeof(struct bnx2x_vf_mac_vlan_filter) +
-	      sizeof(struct bnx2x_vf_mac_vlan_filters);
-
-	fl = kzalloc(fsz, GFP_KERNEL);
+	fl = kzalloc(struct_size(fl, filters, tlv->n_mac_vlan_filters),
+		     GFP_KERNEL);
 	if (!fl)
 		return -ENOMEM;