[media] radio-sf16fmr2: convert to generic TEA575x interface

Convert radio-sf16fmr2 to use generic TEA575x implementation. Most of the
driver code goes away as SF16-FMR2 is basically just a TEA5757 tuner
connected to ISA bus.
The card can optionally be equipped with PT2254A volume control (equivalent
of TC9154AP) - the volume setting is completely reworked (with balance control
added) and tested.
Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

sound/pci/Kconfig

@@ -565,8 +565,8 @@ config SND_FM801_TEA575X_BOOL
 
 config SND_TEA575X
 	tristate
-	depends on SND_FM801_TEA575X_BOOL || SND_ES1968_RADIO
-	default SND_FM801 || SND_ES1968
+	depends on SND_FM801_TEA575X_BOOL || SND_ES1968_RADIO || RADIO_SF16FMR2
+	default SND_FM801 || SND_ES1968 || RADIO_SF16FMR2
 
 source "sound/pci/hda/Kconfig"