mmc: matsushita-common: Handle Renesas div-by-1

On the Renesas version of the IP, the /1 divider is realized by
setting the clock register [7:0] to 0xff instead of setting bit
10 of the register. Check the quirk and handle accordingly.

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