[ALSA] ASoC DAPM switching for reentrant codec paths

This patch fixes an issue whereby power was applied to any inactive
analog path that would leave and reenter a codec (e.g. ACOP -> ACIN on
WM8753).  This change now checks for such paths and DAPM will power them
down when not in use.

Signed-off-by: Seth Forshee <seth.forshee@gmail.com>
Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>