Fix SF security vulnerability: 32660278

Because of lack of mutex lock when get mSidebandStream, if one thread
getSidebandStream, another thread setSidebandStream frequently, an UAF
will be triggered.

Bug: 32660278
Test: Marlin device with poc
Change-Id: Idbcf0976ce2db682d0f13455105c45a5c7481a45
(cherry picked from commit 2d8a2432)