ASoC: cirrus: i2s: Prepare clock before using it

Use clk_prepare_enable()/clk_disable_unprepare() in preparation for switch
to Common Clock Framework, otherwise the following is visible:

WARNING: CPU: 0 PID: 97 at drivers/clk/clk.c:1011 clk_core_enable+0x9c/0xbc
Enabling unprepared mclk
...
Hardware name: Cirrus Logic EDB9302 Evaluation Board
...
clk_core_enable
clk_core_enable_lock
ep93xx_i2s_hw_params
snd_soc_dai_hw_params
soc_pcm_hw_params
snd_pcm_hw_params
snd_pcm_ioctl
...

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211018103105.146380-2-alexander.sverdlin@gmail.com

'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>