brcm63xx: Add Observa VH4032N support

Add support for the Observa Telecom VH4032N router.

This is another BCM6368 router, 128 MB RAM, 32MB flash and 3 USB
host ports.

The wifi chip is an onboard Broadcom BCM43222.

Signed-off-by: Daniel Gonzalez Cabanelas <dgcbueu@gmail.com>
[jonas.gorski: use gpio-hog instead of abusing ephy-reset]
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>