drivers: atm: nicstar: Use the correct function to free some resources

In 'get_scq', 'dma_alloc_coherent' has been used to allocate some
resources, so we need to free them using 'dma_free_coherent' instead
of 'kfree'.

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