net: broadcom: convert to devm_platform_ioremap_resource_byname()

Use the function devm_platform_ioremap_resource_byname() to simplify
source code which calls the functions platform_get_resource_byname()
and devm_ioremap_resource(). Remove also a few error messages which
became unnecessary with this software refactoring.

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