Use String8/16 c_str [camera]

Bug: 295394788
Test: make checkbuild
Change-Id: I321053f5a82ca2e1ad9ea447f96e81a87c3fcfe0
diff --git a/camera/ndk/impl/ACameraMetadata.cpp b/camera/ndk/impl/ACameraMetadata.cpp
index 05124c0..7935909 100644
--- a/camera/ndk/impl/ACameraMetadata.cpp
+++ b/camera/ndk/impl/ACameraMetadata.cpp
@@ -142,7 +142,7 @@
         if (ids[i] == '\0') {
             if (start != i) {
                 mStaticPhysicalCameraIdValues.push_back(String8((const char *)ids+start));
-                mStaticPhysicalCameraIds.push_back(mStaticPhysicalCameraIdValues.back().string());
+                mStaticPhysicalCameraIds.push_back(mStaticPhysicalCameraIdValues.back().c_str());
             }
             start = i+1;
         }