dfu: Shrink code by 144 bytes (by not calling PIO_InitializeInterrupts)

We are not using any PIO interrupts from DFU mode.  It's only used in
the main application firmware (verified by "git grep PIO_ConfigureIt")

Change-Id: Id1447af519df3183061f3d3f156a8dd84789af16

firmware/apps/dfu/main.c

@@ -265,8 +265,6 @@ extern int main(void)
 	PIO_Clear(&pinsLeds[LED_NUM_GREEN]);
 #endif
 
-	PIO_InitializeInterrupts(0);
-
 	EEFC_ReadUniqueID(g_unique_id);
 
 	printf("\n\r\n\r"