accel/qaic: Declare BO 'sliced' after all the operations are complete

Once the BO is declared 'sliced' by setting bo->sliced to true we can
perform DMA (QAIC_EXECUTE_BO) operation on that BO. Hence we should
declare a BO sliced after completing all the operations.

Adding BO to its respective DBC list in qaic_attach_slicing_bo() seems
out of place as qaic_attach_slicing_bo() should just update BO with
slicing configuration.

Signed-off-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230901172247.11410-4-quic_jhugo@quicinc.com