ASoC: tas2781: Use of_property_read_reg()

Replace the open-coded parsing of "reg" with of_property_read_reg().
The #ifdef is also easily replaced with IS_ENABLED().

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20240702215402.839673-1-robh@kernel.org


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