phy-rcar-usb: correct base address

The memory region that is used by the driver overlaps EHCI and OHCI  register
regions for absolutely no reason now  -- fix it  by adding offset of 0x800 to
the base address, changing the register #define's accordingly. This has extra
positive effect that we now can use devm_ioremap_resource()...

Note that the driver and the SoC code have to be in one patch to keep the code
bisectable...

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>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>