ALSA: hda/sigmatel - Fix inverted mute LED

While refactoring the mute-LED handling for HP laptops, I messed up
the polarity check in a wrong way.  The red (or the mute-LED if any)
should appear in the muted state, corresponding to GPIO on.

Reported-by: Mikko Vinni <mmvinni@yahoo.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>