n9: add proximity/light sensor

apds990x driver from 2.6 kernel was ported (the one from 3.5 doesn't
create miscdevice /dev/apds990x0 needed by sensord) together with
board entries.
At the sam time non functional OMAP_GPIO_IRQ was removed and replaced
with gpio_to_irq entries.

Signed-off-by: Filip Matijević <filip.matijevic.pz@gmail.com>
n9: add magnetometer driver

ak8975 driver from 2.6 kernel was ported (the one from 3.5 was dropped)
together with board entries.

Signed-off-by: Filip Matijević <filip.matijevic.pz@gmail.com>