ASoC: sti: fix missing clk_disable_unprepare() on error in uni_player_start()

Fix the missing clk_disable_unprepare() before return
from uni_player_start() in the error handling case.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>