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: f9ad754 ("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>

sound/soc/sof/imx/Kconfig

@@ -11,17 +11,26 @@ config SND_SOC_SOF_IMX_TOPLEVEL
 
 if SND_SOC_SOF_IMX_TOPLEVEL
 
+config SND_SOC_SOF_IMX_OF
+	def_tristate SND_SOC_SOF_OF
+	select SND_SOC_SOF_IMX8 if SND_SOC_SOF_IMX8_SUPPORT
+	help
+	  This option is not user-selectable but automagically handled by
+	  'select' statements at a higher level
+
 config SND_SOC_SOF_IMX8_SUPPORT
 	bool "SOF support for i.MX8"
-	depends on IMX_SCU
-	select IMX_DSP
 	help
 	  This adds support for Sound Open Firmware for NXP i.MX8 platforms
 	  Say Y if you have such a device.
 	  If unsure select "N".
 
 config SND_SOC_SOF_IMX8
-	def_tristate SND_SOC_SOF_OF
-	depends on SND_SOC_SOF_IMX8_SUPPORT
+	tristate
+	depends on IMX_SCU
+	select IMX_DSP
+	help
+	  This option is not user-selectable but automagically handled by
+	  'select' statements at a higher level
 
 endif ## SND_SOC_SOF_IMX_IMX_TOPLEVEL