dmaengine: ep93xx: Prepare clock before using it

dmaengine: ep93xx: 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: 1 at drivers/clk/clk.c:1011 clk_core_enable+0x9c/0xbc
Enabling unprepared m2p0
...
Hardware name: Cirrus Logic EDB9302 Evaluation Board
...
clk_core_enable
clk_core_enable_lock
ep93xx_dma_alloc_chan_resources
dma_chan_get
find_candidate
__dma_request_channel
snd_dmaengine_pcm_request_channel
dmaengine_pcm_new
snd_soc_pcm_component_new
soc_new_pcm
snd_soc_bind_card
edb93xx_probe
...
ep93xx-i2s ep93xx-i2s: Missing dma channel for stream: 0
ep93xx-i2s ep93xx-i2s: ASoC: error at snd_soc_pcm_component_new on ep93xx-i2s: -22
edb93xx-audio edb93xx-audio: ASoC: can't create pcm CS4271 HiFi :-22
edb93xx-audio edb93xx-audio: snd_soc_register_card() failed: -22
edb93xx-audio: probe of edb93xx-audio failed with error -22

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210726140001.24820-6-nikita.shubin@maquefel.me
Signed-off-by: Vinod Koul <vkoul@kernel.org>