PCI: dwc/intel-gw: Drop unnecessary checking of DT 'device_type' property

A driver doesn't need to check for DT 'device_type' property, so let's
remove the check.

Link: https://lore.kernel.org/r/20200821035420.380495-37-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Dilip Kota <eswara.kota@linux.intel.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>