Although one weird behavior about the input path (inconsistent D0/D3
switch) on Cirrus CS420x codecs was fixed in the previous commit,
there is still an issue on some Mac machines: the capture stream
stalls when switching the ADCs on the fly.  More badly, this keeps
stuck until the next reboot.

The dynamic ADC switching is already a bit fragile and assuming
optimistically that the chip accepts the frequent power changes.  On
Cirrus codecs, this doesn't seem applicable.

As a quick workaround, we pin down the ADCs to keep up in D0 when
spec->dyn_adc_switch is set.  In this way, the ADCs are kept up only
for the system that were confirmed to be broken.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=116171
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Takashi Iwai <tiwai@suse.de>