Fix unnecessary copy initialization warnings

Bug: 30413862
Test: build with WITH_TIDY=1
Change-Id: I5de56c163d26e7522141ca06020321c481eea233
diff --git a/camera/common/1.0/default/VendorTagDescriptor.cpp b/camera/common/1.0/default/VendorTagDescriptor.cpp
index bc18270..219d10c 100644
--- a/camera/common/1.0/default/VendorTagDescriptor.cpp
+++ b/camera/common/1.0/default/VendorTagDescriptor.cpp
@@ -258,7 +258,7 @@
 
     for (size_t i = 0; i < static_cast<size_t>(tagCount); ++i) {
         uint32_t tag = tagArray[i];
-        String8 sectionString = tagToSectionMap.valueFor(tag);
+        const String8& sectionString = tagToSectionMap.valueFor(tag);
 
         // Set up tag to section index map
         ssize_t index = sections.indexOf(sectionString);