ARM: dts: aspeed: Add G5 USB Virtual Hub

This adds the (disabled by default) device node for the
Aspeed virtual hub,a long with clocks and pinmux.

This also adds the missing pinmux definition for it
(the kernel driver already knows about it).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>