of/pci: Add of_pci_dma_configure() to update DMA configuration

Add of_pci_dma_configure() to allow updating the DMA configuration of the
PCI device using the configuration from DT of the parent of the root bridge
device.  Use the newly added APIs pci_get/put_host_bridge_device() for
implementing this.

[bhelgaas: fold in fix for host bridges with no parent OF device]
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> (AMD Seattle)
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Rob Herring <robh+dt@kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
CC: Joerg Roedel <joro@8bytes.org>
CC: Grant Likely <grant.likely@linaro.org>
CC: Russell King <linux@arm.linux.org.uk>
CC: Arnd Bergmann <arnd@arndb.de>