arm: global_data: add scu_dev for i.MX8

Add scu_dev for i.MX8, this will be used as a handle
to communite with SCU from A35.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/include/asm/global_data.h b/arch/arm/include/asm/global_data.h
index 287a7bd..c3ee5f0 100644
--- a/arch/arm/include/asm/global_data.h
+++ b/arch/arm/include/asm/global_data.h
@@ -74,6 +74,10 @@
 #if defined(CONFIG_FSL_LSCH3) && defined(CONFIG_SYS_FSL_HAS_DP_DDR)
 	unsigned long mem2_clk;
 #endif
+
+#ifdef CONFIG_ARCH_IMX8
+	struct udevice *scu_dev;
+#endif
 };
 
 #include <asm-generic/global_data.h>