ASoC: imx-wm8962: Remove machine driver

fsl-asoc-card machine driver also handles wm8962, so there is
really no need for keeping the dedicated imx-wm8962 driver anymore.

Remove the imx-wm8962 machine driver.

Suggested-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>