modules: camera: simplify metadata list traversal

keep traveling pointer local to the walking loop

Change-Id: I0038007d6e7a45e519b9b2162c674132477879cc
diff --git a/modules/camera/Metadata.cpp b/modules/camera/Metadata.cpp
index b26986d..d5854f9 100644
--- a/modules/camera/Metadata.cpp
+++ b/modules/camera/Metadata.cpp
@@ -167,8 +167,6 @@
 
 camera_metadata_t* Metadata::generate()
 {
-    Entry *current;
-
     pthread_mutex_lock(&mMutex);
     // Reuse if old generated metadata still valid
     if (!mDirty && mGenerated != NULL) {
@@ -191,7 +189,7 @@
         goto out;
     }
     // Walk list of entries adding each one to newly allocated metadata
-    for (current = mHead; current != NULL; current = current->mNext) {
+    for (Entry *current = mHead; current != NULL; current = current->mNext) {
         int res = add_camera_metadata_entry(mGenerated, current->mTag,
                 current->mData, current->mCount);
         if (res != 0) {