mmc: uniphier-sd: Add support for 64bit controller
The Renesas RCar Gen3 contains the same controller, originally
Matsushita, yet the register addresses are shifted by 1 to the
left. The whole controller is also 64bit, including the data
FIFOs and RSP registers. This patch adds support for handling
the register IO by shifting the register offset by 1 in the IO
accessor functions.