C2SoftVideoDec: Initialize result field in C2Work

final outcome of the work is not initialized during cloneAndSend. This
is now set to C2_OK.

Also call cloneAndSend for configUpdate only if it is not already done.

Bug: 425444898
Bug: 414353388
Test: atest MctsMediaV2TestCases
Test: atest MctsMediaDecoderTestCases
Test: atest VtsHalMediaC2V1_0TargetVideoDecTest
Flag: EXEMPT bugfix
Change-Id: I2b6bef324abbd7bebdfa65d877e324e85df9f1a3