ARM: shmobile: r8a7778: add USB Func DMAEngine support

HPB-DMAC has 2 channel for USB Func (= D0/D1)
D0 is used as Tx, D1 is used as Rx on this patch

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>