imx: mx7: fix build warning when CONFIG_IMX_RDC not enabled

Fix build warning when CONFIG_IMX_RDC not defined in defconfig.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>

arch/arm/mach-imx/mx7/soc.c

@@ -31,7 +31,7 @@ U_BOOT_DEVICE(imx7_thermal) = {
 };
 #endif
 
-#ifdef CONFIG_IMX_RDC
+#if CONFIG_IS_ENABLED(IMX_RDC)
 /*
  * In current design, if any peripheral was assigned to both A7 and M4,
  * it will receive ipg_stop or ipg_wait when any of the 2 platforms enter
@@ -245,8 +245,9 @@ int arch_cpu_init(void)
 	mxs_dma_init();
 #endif
 
-	if (IS_ENABLED(CONFIG_IMX_RDC))
-		isolate_resource();
+#if CONFIG_IS_ENABLED(IMX_RDC)
+	isolate_resource();
+#endif
 
 	return 0;
 }