ARM: dts: NSP: Add bcm958623hr board name to dts

This board was previously added to
Documentation/devicetree/bindings/arm/bcm/brcm,nsp.yaml
however the dts file was not updated to reflect this change. This patch
corrects bcm958623hr.dts by adding the board name to the compatible.

Signed-off-by: Matthew Hagan <mnhagan88@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>