ASoC: SOF: ipc: Remove snd_sof_dsp_mailbox_init()

The snd_sof_dsp_mailbox_init() is called only from sof_get_windows()
to set the sdev->dsp_box.offset/size and sdev->host_box.offset/size

Instead of using a function, set the offsets and sizes like we do for the
other boxes in sof_get_windows().

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20210915122116.18317-3-peter.ujfalusi@linux.intel.com


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