The platform device is created at:
of_platform_default_populate_init: arch_initcall_sync
->of_platform_populate
->of_platform_device_create_pdata
When entering our probe, all the devices should be already created.
if it is null, means NODEV. Currently we don't get the fail case.
It's a minor fix, no need add fixes tags.
Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx>