ARM: shmobile: remove additional __io() macro use

setup-r8a7779.c has grown a new user of the __io() macro. Rob Herring's
PIO cleanup series already gets rid of all other uses in shmobile, so
we should ensure that this one gets removed as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>