HP Spectre x360 14 model (PCI SSID 103c:87f7) seems requiring a unique
setup for its external amp: the GPIO0 needs to be toggled on and off
shortly at each device initialization via runtime PM.

This patch implements that workaround as well as the model option
string, so that users with other devices may try the same workaround
more easily.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=210633
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210215082540.4520-1-tiwai@suse.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>