Don't depend on String8 cast to C string [drm]

Bug: 295394788
Test: m checkbuild
Change-Id: Ie9b5530e5a1c726bd723ebd7e11a745893269acf
diff --git a/drm/1.0/default/DrmPlugin.cpp b/drm/1.0/default/DrmPlugin.cpp
index dfa5d22..0a0a350 100644
--- a/drm/1.0/default/DrmPlugin.cpp
+++ b/drm/1.0/default/DrmPlugin.cpp
@@ -133,8 +133,8 @@
         Vector<KeyValue> infoMapVec;
         for (size_t i = 0; i < legacyInfoMap.size(); i++) {
             KeyValue keyValuePair;
-            keyValuePair.key = String8(legacyInfoMap.keyAt(i));
-            keyValuePair.value = String8(legacyInfoMap.valueAt(i));
+            keyValuePair.key = legacyInfoMap.keyAt(i);
+            keyValuePair.value = legacyInfoMap.valueAt(i);
             infoMapVec.push_back(keyValuePair);
         }
         _hidl_cb(toStatus(status), toHidlVec(infoMapVec));