usb: renesas_usbhs: support byte addressable CFIFO

Some SoC have a CFIFO register that is byte addressable. This means
when the CFIFO access is set to 32-bit, you can write 8-bit values to
addresses CFIFO+0, CFIFO+1, CFIFO+2, CFIFO+3.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>