phy-rcar-usb: handle platform data

Set the USBPCTRL0 register from the passed platform data in rcar_usb_phy_init();
don't reset it to 0 in  rcar_usb_phy_shutdown()  anymore as that does not make
sense.  Also, don't allow the driver's probe to succeed when the platform data
are not supplied with a device.

The patch has been tested on the Marzen and BOCK-W boards.

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