i2c: gpio: Augment all boardfiles to use open drain

We now handle the open drain mode internally in the I2C GPIO
driver, but we will get warnings from the gpiolib that we
override the default mode of the line so it becomes open
drain.

We can fix all in-kernel users by simply passing the right
flag along in the descriptor table, and we already touched
all of these files in the series so let's just tidy it up.

Cc: Steven Miao <realmz6@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Wu, Aaron <Aaron.Wu@analog.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>