pbio/drv/core: Move ADC init to normal start location.

This completes the transition started in the previous commit. The ADC does not depend on anything other than clocks, so we can move it along with the other drivers.

Author: laurensvalk

lib/pbio/drv/core.c

@@ -39,6 +39,7 @@ void pbdrv_init(void) {
     process_start(&etimer_process);
 
     // the rest of the drivers should be implemented so that init order doesn't matter
+    pbdrv_adc_init();
     pbdrv_battery_init();
     pbdrv_block_device_init();
     pbdrv_bluetooth_init();
@@ -79,8 +80,4 @@ void pbdrv_init(void) {
     // devices behaves the same as if unknown devices are still syncing up after
     // just being plugged in.
     pbdrv_legodev_init();
-
-    // REVISIT: verify that the order does not matter and that we can start this
-    // in the same place as the other drivers above.
-    pbdrv_adc_init();
 }