[ALSA] hda-codec - Add EAPD controls for ALC260 test model

This implements a switch control for the EAPD signal output by the ALC26x
chips.  Since some laptops may utilise this to activate useful things it
is handy to have a control for this in the ALC26x test models.  The patch
includes the control in the ALC260 test model.

Signed-off-by: Jonathan Woithe <jwoithe@physics.adelaide.edu.au>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>