message_parsers: Use const reference where possible

The code was passing std::shared_ptr<xxx> by value (or const value),
which creates unnecessary copies of shared_ptr.

Use `const std::shared_ptr<xxx>&` where possible to eliminate such
copies.

Tested: No code logic changes. Verify the build passes and the net-ipmid
        is working as before.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: Iad6c3b209ab8299fa477784e86c22be19f98a344
2 files changed