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: NJonathan Woithe <jwoithe@physics.adelaide.edu.au>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>