ASoC: dapm: Add new widgets to the end of the widget list

Currently new widgets are appended to the beginning of the cards widget
list. This has the effect that widgets that are created while iterating
over the widget list in snd_soc_dapm_new_widgets() (like e.g. the
auto-disable widgets) are not covered during that invocation of the
function. If no further invocations of snd_soc_dapm_new_widgets() happen
these widgets will not be fully initialized and e.g. no debugfs entries are
created for them.

By adding new widgets to the end of the widget list we make sure that
widgets that are created in snd_soc_dapm_new_widgets() will still be
handled during the same snd_soc_dapm_new_widgets() invocation and are
always fully initialized.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>