[ALSA] hda-codec - Disable PCBEEP mixer element in test model

It turned out that the PCBEEP element (0x1d) is disabled on some hardwares
although it's defined in the datasheet.  Because of the error at info of
this element, the mixer gets totally unusable.
Since the PCBEEP isn't that important feature, it's safer to disable this.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>