Powering a device through GPIO
The i.MX28 datasheet says:



You have to check whether these currents are enough for your secondary board.

Please note that these limits are for the specified voltage drops; if you draw less current, the voltage will be higher than 0.8×VDDIO, and if you draw more (which is possible), the voltage will drop even more. (So it might make sense to configure "High" drive strength even if you need only 5 mA.)