io: change outX() to have their own IO barrier overrides

Open code writeX() inside outX() so that outX() variants have their own
overrideable Port IO barrier combinations as __io_pbw() and __io_paw() for
actions to be taken before port IO and after port IO write.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>