ipq806x: refactor ipq8065 device tree

ipq806x: refactor ipq8065 device tree

At the moment we have 2 seperate device tree sources: 1 for ipq8064 soc located
in kernel source and 1 custom in LEDE for ipq8065.
ipq8064 and ipq8065 SoCs are completely identical except ipq8065 has higher cpu
frequencies and adjusted corresponding power supply.

This commit makes ipq8065 DTS to contain only specific for ipq8065 DT entries while
pulling all the basic SoC stuff from ipq8064 DTS.

It makes easier to manage ipq806x device trees and instead of committing changes into
2 seperate equal DTS we are ending up with only 1.
It also enables ipq8065 devices to automatically receive changes made in upstream kernel.

Signed-off-by: Pavel Kubelun <be.dissent@gmail.com>