Camera: Remove an unused variable mCameraMuteChanged in Camera3Device

mCameraMuteChanged is currently doing nothing.

Test: m
Change-Id: I0e8dc10cda56a93e4776781ca302aabc4cf4b4da
(cherry picked from commit e92479266ba7e0de2c5307ed280a603c82b70b66)
2 files changed