ASoC: soc-dapm: Include quotes around contents in debugfs entries

Sometimes the name of the control switch of a dapm route contains
spaces which makes it impossible to distinguish it from the source widget.
Add quotes around the names of the widgets to makes these parsable.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>