mmc: renesas-sdhi: Handle 16bit IP

mmc: renesas-sdhi: Handle 16bit IP

The Renesas RCar Gen2 chips have a mix of 32bit and 16bit variants
of the IP. There is no DT property which allows discerning those,
so what Linux does is it checks the size of the register area and
if it is 0x100, the IP is 16bit, otherwise the IP is 32bit. Handle
the distinction the same way.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>