ARM: dts: berlin: add BG2Q nodes for USB support

Adds nodes describing the Marvell Berlin BG2Q USB PHY and USB. The BG2Q
SoC has 3 USB host controller, compatible with ChipIdea.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>