ASoC: SOF: Turn "firmware boot complete" message into a dbg message

Using a Canon Lake machine with the SOF driver causes dmesg to fill
up with a ton of these messages:

[  275.902194] sof-audio-pci 0000:00:1f.3: firmware boot complete
[  351.529358] sof-audio-pci 0000:00:1f.3: firmware boot complete
[  560.049047] sof-audio-pci 0000:00:1f.3: firmware boot complete
etc.

Since the DSP is powered down when not in used this happens everytime
e.g. a notification plays, polluting dmesg.

Turn this messages into a debug message, matching what the code already
does for the ""booting DSP firmware" message.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200402184948.3014-2-hdegoede@redhat.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/loader.c

@@ -597,7 +597,7 @@ int snd_sof_run_firmware(struct snd_sof_dev *sdev)
 	}
 
 	if (sdev->fw_state == SOF_FW_BOOT_COMPLETE)
-		dev_info(sdev->dev, "firmware boot complete\n");
+		dev_dbg(sdev->dev, "firmware boot complete\n");
 	else
 		return -EIO; /* FW boots but fw_ready op failed */