phy-rcar-usb: add platform data

Currently the driver hard-codes  USBPCTRL0 register to 0. It is wrong since this
register contains board-specific USB ports configuration and so its value should
be somehow passed via the platform data.  Add the global header file containing
'struct rcar_phy_platform_data' consisting of the various bit fields describing
USB ports' pin configuration.

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