ASoC: SOF: Add helper function to prepare and send an IPC message

The new sof_ipc_send_msg() can be used by IPC dependent code to prepare
the ipc->msg for a new message transmission and then call in to platform
code to send the message.

Higher level code should be handling the completion and reply.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220405172708.122168-2-ranjani.sridharan@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>