ASoC: tas2781: fix Kconfig dependencies

The new driver has two modules that both get enabled for build testing
when all codecs are selected. The comlib part has an i2c dependency,
so this remains disabled on builds without i2c, but then the other
one fails to link:

ERROR: modpost: "tasdevice_dev_bulk_write" [sound/soc/codecs/snd-soc-tas2781-fmwlib.ko] undefined!
ERROR: modpost: "tasdevice_dev_update_bits" [sound/soc/codecs/snd-soc-tas2781-fmwlib.ko] undefined!
ERROR: modpost: "tasdevice_dev_bulk_read" [sound/soc/codecs/snd-soc-tas2781-fmwlib.ko] undefined!
ERROR: modpost: "tasdevice_dev_read" [sound/soc/codecs/snd-soc-tas2781-fmwlib.ko] undefined!
ERROR: modpost: "tasdevice_dev_write" [sound/soc/codecs/snd-soc-tas2781-fmwlib.ko] undefined!

There are many ways to address this, adding an explicit dependency seems
to be the clearest method that keeps the structure of the driver otherwise
unchanged.

Fixes: ef3bcde7 ("ASoC: tas2781: Add tas2781 driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/Message-Id

: <20230622101205.3180938-1-arnd@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>