Gnss Hal Minor Cleanup

Enum sizes and names cleaned up, fixed errors in comments,
cleaned up some variable names.

Also removed AGnssRefLocation since it appears to be unused.

Bug:31974439
Test: mm

Change-Id: I88f43caac5ce9c7137e28b29ba55ea330786745f
diff --git a/gnss/1.0/IGnssMeasurement.hal b/gnss/1.0/IGnssMeasurement.hal
index 5156b32..5174273 100644
--- a/gnss/1.0/IGnssMeasurement.hal
+++ b/gnss/1.0/IGnssMeasurement.hal
@@ -43,7 +43,7 @@
      * Returns ERROR_GENERIC for any other error. The HAL must
      * not generate any other updates upon returning this error code.
      */
-    setCallback(IGnssMeasurementCallback callback) generates (int32_t initRet);
+    setCallback(IGnssMeasurementCallback callback) generates (GnssMeasurementStatus initRet);
 
     /*
      * Stops updates from the HAL, and unregisters the callback routines.