gpio: adp5588: get value from data out when dir is out

gpio: adp5588: get value from data out when dir is out

As discussed here: http://ez.analog.com/message/35852,
the 5587 revC and 5588 revB spec sheets contain a mistake
in the GPIO_DAT_STATx register description.

According to R.Shnell at ADI, as well as my own
observations, it should read:
"GPIO data status (shows GPIO state when read for inputs)".

This commit changes the get value function accordingly.

Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>