Since only one event can be associated to a (pin) widget, it's safer
to avoid the multiple mapping.  This patch fixes the behavior of the
STAC/IDT codec driver.

Now stac_get_event() doesn't take the type argument but simply returns
the first hit element.  Then enable_pin_detect() checks the validity
of the type, and returns non-zero only if a valid entry.  The caller
can call stac_issue_unsol_event() after checking the return value.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>