atm: nicstar: Use kcalloc() to simplify code

Use kcalloc() instead of kmalloc_array() and a loop to set all the values
of the array to NULL.

While at it, remove a duplicated assignment to 'scq->num_entries'.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>