Camera: Don't cancel AF when the device is disconnected

Under some conditions camera clients may be able to
call 'cancelAutoFocus' immediately after the
Camera2Client disconnects from the Camera3Device.
The device instance will remain valid but some
of the internal resources like the request thread
will be released.
Avoid possible invalid access by checking the
client parameter state and return appropriate
error status in case we are disconnected.

Bug: 323947800
Test: atest -c -d cts/tests/camera/src/android/hardware/cts/
Change-Id: I6e777212168ac92a28cc7b1bc16c7a0eeb7dbb2d