of_device_get_match_data() was added in v4.2 to reduce the the boilerplate
required to get at SoC-specific data.  Use it to simplify the code
slightly.

[bhelgaas: changelog]
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>