ASoC: simple_card_utils.h: Add missing include

ASoC: simple_card_utils.h: Add missing include

When debug is enabled compiler cannot find the definition of
clk_get_rate resulting in the following error:

./include/sound/simple_card_utils.h:168:40: note: previous implicit
declaration of ‘clk_get_rate’ was here
   dev_dbg(dev, "%s clk %luHz\n", name, clk_get_rate(dai->clk));
./include/sound/simple_card_utils.h:168:3: note: in expansion of macro
‘dev_dbg’
   dev_dbg(dev, "%s clk %luHz\n", name, clk_get_rate(dai->clk));

Fix this by including the appropriate header.

Fixes: 0580dde59438686d ("ASoC: simple-card-utils: add asoc_simple_debug_info()")
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20191009153615.32105-2-daniel.baluta@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>