ALSA: HDA: Add a new model "asus" for Conexant 5066/205xx

BugLink: http://bugs.launchpad.net/bugs/701271

This new model, named "asus", is identical to the "hp_laptop" model,
except for the location of the internal mic, which is at pin 0x1a.
It is used for Asus K52JU and Lenovo G560.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>