cirrus: cs89x0: Use managed interfaces

This patch introduces the use of managed interfaces like
devm_ioremap_resource and does away with the functions to free the
allocated memory in the probe and remove functions. Also, many labels
are done away with. The field size in no longer needed and is hence
removed from the struct net_local.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>