PCI: dwc: Convert to devm_platform_ioremap_resource_byname()

Use devm_platform_ioremap_resource_byname() to simplify the code
since it contains platform_get_resource_byname() and
devm_ioremap_resource() respectively.

Link: https://lore.kernel.org/r/20200708164013.5076-1-zhengdejin5@gmail.com


Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Reviewed-by: Rob Herring <robh@kernel.org>