serial: remove ks8695 driver

The platform is getting removed, so there are no more users
of this driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190809202749.742267-3-arnd@arndb.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>