Fix style violation according to go/droidcppstyle

Local variable should be lowerCamelCase.

This change leave the buffer_state fence_state,
active_clients_bit_mask and queue_index in MetadataHeader unchanged
because there are too many instances of them that need to be changed in
both new bufferhub system and the old pdx-backed bufferhubd system.
I will do a separate change for that.

Test: m, mma
Bug: 68273829
Change-Id: Ia91cf7debe01a402f61171f069988e0ac13cec6a
diff --git a/libs/ui/BufferHubBuffer.cpp b/libs/ui/BufferHubBuffer.cpp
index 7693fcb..cce35fd 100644
--- a/libs/ui/BufferHubBuffer.cpp
+++ b/libs/ui/BufferHubBuffer.cpp
@@ -209,10 +209,10 @@
     }
 
     // Populate shortcuts to the atomics in metadata.
-    auto metadata_header = mMetadata.metadataHeader();
-    mBufferState = &metadata_header->buffer_state;
-    mFenceState = &metadata_header->fence_state;
-    mActiveClientsBitMask = &metadata_header->active_clients_bit_mask;
+    auto metadataHeader = mMetadata.metadataHeader();
+    mBufferState = &metadataHeader->buffer_state;
+    mFenceState = &metadataHeader->fence_state;
+    mActiveClientsBitMask = &metadataHeader->active_clients_bit_mask;
     // The C++ standard recommends (but does not require) that lock-free atomic operations are
     // also address-free, that is, suitable for communication between processes using shared
     // memory.