AM1808 connecting external clock against PRU function pin

Hi,

I have a question about AM1808 pin(A3).

My customer are connecting 48MHz external clock for USB_REFCLKIN against A3 pin of AM1808.
There two type of customer boards. One type of boards doesn't use USB_REFCLKIN, 
so this A3 pin are set to default function(PRU0_R31[17]) but 48MHz clock are still mounted 
and connected to this pin.

They want to know if there are any problem connecting 48MHz clock against PRU0_R31[17] function pin.
Are there any problem like device will get damaged or undesired operation?
By the way, they are not using PRU.

best regards,
g.f.