Fix error exit code for enable_test_camera

Exit codes get truncated to 8-bits in unix systems, as a result STATUS_UNKNOWN_ERROR (-2147483648) gets truncated to all zero's resulting in the interpretation of STATUS_OK (0) during camera creation failure in enable_test_camera cmd for virtual camera. This is fixed by returning EOPNOTSUPP whose 8-bit truncation results in a non-zero value.

Change-Id: Ibd99d264ef104f01056e907648ae0eb15d3015af
Test: atest CtsVirtualDevicesCameraTestCases
Fixes: 392178976, 392179343, 392178913, 392178138, 392178912, 392178137, 392178677, 392178752, 392179009, 392178496, 392178831, 392178944, 392178555, 392179223, 392179024, 392179146, 392041264, 392041148, 392040853
Flag: EXEMPT test fix