ASoC: fsl: fsl-asoc-card: Trivial: Fix misspelling of 'exists'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Cc: Timur Tabi <timur@kernel.org>
Cc: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: Xiubo Li <Xiubo.Lee@gmail.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20200715150009.407442-1-lee.jones@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>