ARM: BCM5301X: Specify USB 3.0 PHY in DT

Driver for Northstar USB 3.0 PHY has been recently added under the name
phy-bcm-ns-usb3. Add binding for it into the DT files.
The only slightly tricky part is BCM47094 which uses different PHY
version and requires different compatible value.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>