net: dnet: Use managed interfaces

This patch introduces the use of managed interfaces like
devm_ioremap_resource and does away with the calls to free the
allocated memory in the probe and remove functions. Also, some
labels and variable are done away with. This fixes a bug as there
was a missing release_mem_region in the remove function.

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>