ARM: shmobile: r8a7779: setup EHCI internal buffer

Setup the EHCI internal buffer (before EHCI driver has a chance to touch the
registers) using the pre_setup() method in 'struct usb_ehci_pdata'.

The patch has been tested on the Marzen board.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>