Remove redundant @GuardedBy's in HdmiCecLocalDevice.

@GuardedBy is unnecessary in HdmiCecLocalDevice#getDeviceInfo and
HdmiCecLocalDevice#setDeviceInfo because those methods already acquire
the lock. This CL removes these @GuardedBy annotations and all
synchronized blocks added because of them.

Test: make
Bug: 215321161
Change-Id: Ic334fda703ef057f2e0ecd88919fa55148ac97eb