imx8: add cpu support

Add cpu type and Kconfig entry

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx8/Kconfig b/arch/arm/mach-imx/imx8/Kconfig
index f76a139..4336a8c 100644
--- a/arch/arm/mach-imx/imx8/Kconfig
+++ b/arch/arm/mach-imx/imx8/Kconfig
@@ -10,6 +10,11 @@
 	  SPL runs in EL3 mode, it use MU0_A to communicate with SCU.
 	  So we could not reuse the one in dts which is for normal U-Boot.
 
+config IMX8QM
+	select IMX8
+	select SUPPORT_SPL
+	bool
+
 config IMX8QXP
 	select IMX8
 	select SUPPORT_SPL