ASoC: SOF: stream-ipc: Check for cstream nullity in sof_ipc_msg_data()

In the Linux kernel, the following vulnerability has been resolved: ASoC: SOF: stream-ipc: Check for cstream nullity in sof_ipc_msg_data() The nullity of sps->cstream should be checked similarly as it is done in sof_set_stream_data_offset() function. Assuming that it is not NULL if sps->stream is NULL is incorrect and can lead to NULL pointer dereference.