ASoC: SOF: Add missing dependency on IMX_SCU

This broke PowerPC allyesconfig.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20200423142805.52757-1-broonie@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/imx/Kconfig

@@ -21,6 +21,7 @@ config SND_SOC_SOF_IMX_OF
 
 config SND_SOC_SOF_IMX8_SUPPORT
 	bool "SOF support for i.MX8"
+	depends on IMX_SCU
 	help
 	  This adds support for Sound Open Firmware for NXP i.MX8 platforms
 	  Say Y if you have such a device.