ARM: dts: NSP: Add new DT file for bcm958623hr

Create a new device tree file for the Broadcom Northstar Plus
bcm958623hr SVK.  This SVK has 2GB RAM, 5 ports Ethernet, SATA, 2 PCI
slots, and 1 UART.  Also, it has the ability to reboot via GPIO.  To be
added in the future are support for the USB and SLIC audio.

Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>