soc: imx: check ls1021a

fsl,ls1021a is a mach under arch/arm/mach-imx/, however it could
not use the soc driver which will break caam on ls1021a platform.

So directly return if it is compatible with fsl,ls1021a.

Fixes: 52102a3ba6a61 ("soc: imx: move cpu code to drivers/soc/imx")
Signed-off-by: Peng Fan <[e-mail]>
Tested-by: Horia Geantă <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

drivers/soc/imx/soc-imx.c

···
 	u32 val;
 	int ret;
 
+	if (of_machine_is_compatible("fsl,ls1021a"))
+		return 0;
+
 	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
 	if (!soc_dev_attr)
 		return -ENOMEM;