PCI: Remove PCIe Kconfig dependencies on PCI

drivers/pci/pcie/Kconfig is only sourced by drivers/pci/Kconfig, and only
when PCI is defined, so there's no need to depend on PCI again.  Remove the
unnecessary dependencies.

Link: https://lore.kernel.org/r/20191106222420.10216-5-helgaas@kernel.org


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>