ASoC: core: Fix pcm code debugfs error

We can have 2 dcpm-s with the same backend and frontend name
(capture + playback pair), this causes the following debugfs error
on Intel Bay Trail systems:

[  298.969049] debugfs: Directory 'SSP2-Codec' with parent 'Baytrail Audio Port' already present!

This commit adds a ":playback" or ":capture" postfix to the debugfs dir
name fixing this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20191005212202.5206-1-hdegoede@redhat.com


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