PCI: j721e: Drop redundant struct device *

The struct cdns_pcie already contains the struct device for the j721e PCIe
controller.  There's no need to store another copy in struct j721e_pcie.
Remove the redundant copy from struct j721e_pcie.

Link: https://lore.kernel.org/r/20211223011054.1227810-10-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Tom Joseph <tjoseph@cadence.com>