net: ethernet: dnet: convert to devm_platform_get_and_ioremap_resource

use devm_platform_get_and_ioremap_resource() to simplify code, which
contains platform_get_resource() and devm_ioremap_resource(), it also
get the resource for use by the following code.

Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>