PCI: rcar: Add runtime PM support

If runtime PM is enabled in the kernel config, the PCI clocks are not
forced on at start-up, and thus, are never enabled.  Use
pm_runtime_get_sync() to enable the clocks.

While at it, use dev_info() instead of pr_info() since now we have the
device pointer available in the PCI setup callback.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>