firmware: imx: add COMPILE_TEST support

Add COMPILE_TEST support to i.MX SCU drivers for better compile
testing coverage.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1583509356-8265-1-git-send-email-Anson.Huang@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/imx/Kconfig

@@ -12,7 +12,7 @@ config IMX_DSP
 
 config IMX_SCU
 	bool "IMX SCU Protocol driver"
-	depends on IMX_MBOX
+	depends on IMX_MBOX || COMPILE_TEST
 	help
 	  The System Controller Firmware (SCFW) is a low-level system function
 	  which runs on a dedicated Cortex-M core to provide power, clock, and
@@ -24,6 +24,6 @@ config IMX_SCU
 
 config IMX_SCU_PD
 	bool "IMX SCU Power Domain driver"
-	depends on IMX_SCU
+	depends on IMX_SCU || COMPILE_TEST
 	help
 	  The System Controller Firmware (SCFW) based power domain driver.