mmc: matsushita-common: Add missing else

Fix minor rebase omission, the else was missing which triggered
two accesses to the register on 64bit variant of the IP.

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