Fix a android.hardware.cts.CameraTest cts test.

The android.hardware.cts.CameraTest#testParameters test would fail on all
subsequent runs of the android.hardware.cts.CameraTest suite. This is
caused by the android.hardware.cts.CameraTest#testPreviewFormats test changing
the default preview format mode.

Change-Id: I07484d03b695001ada0ec940bc9ab7d3f7652937
Signed-off-by: Douglas Leung <douglas@mips.com>