[ALSA] HDA/ALC260: 2/7 - switch pin buffer enables

Modules: HDA Codec driver

This patch adds functionality which switches the input/output buffer enables
of retasking pins when the user changes their mode with the mode control.
This probably reduces noise *slightly* for recording compared to the case
where both input and output buffers were enabled simultaneously.

Signed-off-by: Takashi Iwai <tiwai@suse.de>