mmc: sh_mmcif: Simplify division/shift logic

"a / (1 << b)" == "a >> b".

No change in generated code.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/68d689c39c769d298b53ee8cb9de0e594a2999b2.1645460780.git.geert+renesas@glider.be


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>