dt-bindings: net: ath10k: fix node name and device type in qcom ath10k example

In qcom,ath10k documentation, ath10k is used as node name in the example of
pci based device. Normally, node name should be class of device and not the
model name, so fix it to node name "wifi". And remove the property device_type
pci since only pci bridges should have this property.

Signed-off-by: Bhagavathi Perumal S <bperumal@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>