ASoC: SOF: Make Intel IPC stream ops generic

ASoC: SOF: Make Intel IPC stream ops generic

This operations should be generic as there is nothing Intel
specific. This works well for NXP i.MX8 stream IPC ops.

We start by moving sof/intel/intel-ipc.c into sof/stream-ipc.c and
rename the functions to be generic.

Notice that we use newly introduced snd_sof_dsp_mailbox_read
instead of sof_mailbox_read, to make sure that we are not
bound to existing MMIO memory access, and we allow platform
to implement their own memory access routines.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Bud Liviu-Alexandru <budliviu@gmail.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@gmail.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20211004152147.1268978-3-daniel.baluta@oss.nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>