ALSA: hda - Add quirk for HP6730B laptop

Added model=laptop for HP 6730B laptop with AD1984A codec.
Reference: Novell bnc#457909
	https://bugzilla.novell.com/show_bug.cgi?id=457909



Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: stable@kernel.org