ASoC: ep93xx: i2s: move enable call to startup callback

ASoC: ep93xx: i2s: move enable call to startup callback

Make startup/shutdown callbacks symmetric to avoid clock subsystem warnings
(reproduced with "aplay --dump-hw-params" + ctrl-c):

WARNING: CPU: 0 PID: 102 at drivers/clk/clk.c:1048 clk_core_disable
lrclk already disabled
CPU: 0 PID: 102 Comm: aplay Not tainted 6.2.0-rc4 #1
Hardware name: Generic DT based system
 ...
 clk_core_disable from clk_core_disable_lock
 clk_core_disable_lock from ep93xx_i2s_shutdown
 ep93xx_i2s_shutdown from snd_soc_dai_shutdown
 snd_soc_dai_shutdown from soc_pcm_clean
 soc_pcm_clean from soc_pcm_close
 soc_pcm_close from snd_pcm_release_substream.part.0
 snd_pcm_release_substream.part.0 from snd_pcm_release
 snd_pcm_release from __fput
 __fput from task_work_run
 ...

WARNING: CPU: 0 PID: 102 at drivers/clk/clk.c:907 clk_core_unprepare
lrclk already unprepared
CPU: 0 PID: 102 Comm: aplay Tainted: G        W          6.2.0-rc4 #1
Hardware name: Generic DT based system
 ...
 clk_core_unprepare from clk_unprepare
 clk_unprepare from ep93xx_i2s_shutdown
 ep93xx_i2s_shutdown from snd_soc_dai_shutdown
 snd_soc_dai_shutdown from soc_pcm_clean
 soc_pcm_clean from soc_pcm_close
 soc_pcm_close from snd_pcm_release_substream.part.0
 snd_pcm_release_substream.part.0 from snd_pcm_release
 snd_pcm_release from __fput
 __fput from task_work_run
 ...

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20230410223902.2321834-2-alexander.sverdlin@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>