ARM: dts: BCM5301X: Add basic DT for Phicomm K3

ARM: dts: BCM5301X: Add basic DT for Phicomm K3

This router has BCM4709C0 SoC, 128 MiB NAND flash (MX30LF1G18AC-TI),
512 MiB memory and 3 x LAN and 1 x WAN ports. WiFi chips are
BCM4366C0 x 2. The router has a small LCD and 3 capactive keys driven by
a PIC microcontroller, which is in turn wired to UART1 of main board.

Signed-off-by: Hao Dong <halbertdong@gmail.com>
[rmilecki: drop chosen { }, fix whitespaces, update commit message]
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>