OMAP: GPIO: Fix incorrect gpio_get logic for output GPIOs

gpio_get() should return DATAIN register value when the GPIO
is configured as input whereas it should return DATAOUT register
value when the GPIO is configured as output.
Now /sys/kernel/debug/gpio shows proper values for output GPIOs

Signed-off-by: Roger Quadros <ext-roger.quadros@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>