staging: mt7621-dts: Fix remaining pcie warnings

This currently fixes the remaining dtb warnings:

Node /pcie@1e140000/pcie0 has a reg or ranges property, but no unit name
Node /pcie@1e140000/pcie1 has a reg or ranges property, but no unit name
Node /pcie@1e140000/pcie2 has a reg or ranges property, but no unit name
Node /pcie@1e140000/pcie0 node name is not "pci" or "pcie"
Node /pcie@1e140000/pcie0 missing ranges for PCI bridge (or not a bridge)
Node /pcie@1e140000/pcie0 missing bus-range for PCI bridge
Node /pcie@1e140000/pcie1 node name is not "pci" or "pcie"
Node /pcie@1e140000/pcie1 missing ranges for PCI bridge (or not a bridge)
Node /pcie@1e140000/pcie1 missing bus-range for PCI bridge
Node /pcie@1e140000/pcie2 node name is not "pci" or "pcie"
Node /pcie@1e140000/pcie2 missing ranges for PCI bridge (or not a bridge)
Node /pcie@1e140000/pcie2 missing bus-range for PCI bridge
Warning (unit_address_format): Failed prerequisite 'pci_bridge'
Warning (pci_device_reg): Failed prerequisite 'pci_bridge'
Warning (pci_device_bus_num): Failed prerequisite 'pci_bridge'

device_type was removed since according to documentation, it's deprecated
for pci(e) devices.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>