usb: r8a66597: Replace IO accessors

Replace in{bwl}()/out{bwl}() IO accessors with read{bwl}()/write{bwl}(),
to make the driver compile both on SH and ARM.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Chris Brandt <chris.brandt@renesas.com>