ASoC: SOF: imx: fix undefined reference issue

ASoC: SOF: imx: fix undefined reference issue

make.cross ARCH=mips allyesconfig fails with the following error:

sound/soc/sof/sof-of-dev.o:(.data.sof_of_imx8qxp_desc+0x40): undefined
reference to `sof_imx8x_ops'.

This seems to be a Makefile order issue, solve by using the same
structure as for Intel platforms.

Fixes: 3d851160e9c7 ("ASoC: SOF: imx: fix reverse CONFIG_SND_SOC_SOF_OF
dependency")
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20200409071832.2039-3-daniel.baluta@oss.nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>