Fix bug in error checking in GnssLocationProvider

Needed to check if gnssNiIface was a nullptr
before calling setCallback on it.

Bug: 36052760
Test: make
Change-Id: I4d725bd30310353fb7d248f9bf247ac55f94c765
diff --git a/services/core/jni/com_android_server_location_GnssLocationProvider.cpp b/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
index 36ae94b..78d8b53 100644
--- a/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
+++ b/services/core/jni/com_android_server_location_GnssLocationProvider.cpp
@@ -1175,7 +1175,7 @@
     }
 
     sp<IGnssNiCallback> gnssNiCbIface = new GnssNiCallback();
-    if (gnssNiCbIface != nullptr) {
+    if (gnssNiIface != nullptr) {
         gnssNiIface->setCallback(gnssNiCbIface);
     } else {
         ALOGE("Unable to initialize GNSS NI interface\n");