Currently on each driver reload internal counter is being increased. It
causes failure to enumerate driver devices, as they have hardcoded:
.codec_name = "ehdaudio0D2",
As there is currently no devices with multiple hda codecs and there is
currently no established way to reliably differentiate, between them,
always assign bus->idx = 0;

This fixes a problem when we unload and reload machine driver idx gets
incremented, so .codec_name would've needed to be set to "ehdaudio1D2"
after first reload and so on.
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>