ALSA: virtuoso: fix front panel routing for D1/DX/ST(X)

The "Front Panel" switch on the Xonar D1/DX actually switches only the
output direction, so mark it appropriately.

The front panel microphone is controlled by the FMIC2MIC bit of the
CM9780.  It was unconditionally enabled on the D1/DX and never set on
the ST(X); add a control for it.  Selecting the front panel microphone
as source does not actually disable the microphone jack, but this is
bug-compatible with the Windows driver, and users rely on it.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>