firmware: tegra: bpmp: Use devm_platform_ioremap_resource()

Use the devm_platform_ioremap_resource() helper instead of calling
platform_get_resource() and devm_ioremap_resource() separately.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>