Radio: get service by value.

Get strong pointer to service interface by value and not reference to
prevent race conditions where the service pointer can be cleared
by another thread while in use.

Bug: 30907212
Change-Id: Iae838b3b672562c1d0cd63968399a6bfdda7f5ab
diff --git a/radio/Radio.cpp b/radio/Radio.cpp
index e3554c2..3c04fb0 100644
--- a/radio/Radio.cpp
+++ b/radio/Radio.cpp
@@ -55,7 +55,7 @@
     sp<DeathNotifier>         gDeathNotifier;
 }; // namespace anonymous
 
-const sp<IRadioService>& Radio::getRadioService()
+const sp<IRadioService> Radio::getRadioService()
 {
     Mutex::Autolock _l(gLock);
     if (gRadioService.get() == 0) {
@@ -84,7 +84,7 @@
                             uint32_t *numModules)
 {
     ALOGV("listModules()");
-    const sp<IRadioService>& service = getRadioService();
+    const sp<IRadioService> service = getRadioService();
     if (service == 0) {
         return NO_INIT;
     }
@@ -98,7 +98,7 @@
 {
     ALOGV("attach()");
     sp<Radio> radio;
-    const sp<IRadioService>& service = getRadioService();
+    const sp<IRadioService> service = getRadioService();
     if (service == 0) {
         return radio;
     }