ASoC: tas2781: remove unused acpi_subysystem_id

[ Upstream commit 4089d82e ]

The acpi_subysystem_id is only written and freed, not read, so
unnecessary.

Signed-off-by: Gergo Koteles <soyer@irl.hu>
Link: https://lore.kernel.org/r/454639336be28d2b50343e9c8366a56b0975e31d.1707456753.git.soyer@irl.hu


Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: c2c0b67d ("ASoC: tas2781-i2c: Drop weird GPIO code")
Signed-off-by: Sasha Levin <sashal@kernel.org>