ALSA: es1968: convert TEA575x support to new interface

Use common functions to access TEA575x tuner - remove original read/write
functions and provide new pin manipulation functions instead.

Tested with SF64-PCE2 card.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>