imx: Fix multiple definition of ipc_handle

This is not conforming C and does not compile with -fno-common.
Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: I6535954cc567d6efa06919069b91e3f50975b073

plat/imx/common/include/sci/sci_ipc.h

 /*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -62,6 +62,6 @@ void sc_ipc_read(sc_ipc_t ipc, void *data);
  */
 void sc_ipc_write(sc_ipc_t ipc, void *data);
 
-sc_ipc_t ipc_handle;
+extern sc_ipc_t ipc_handle;
 
 #endif /* SCI_IPC_H */

plat/imx/common/sci/ipc.c

 /*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -13,6 +13,8 @@
 #include <sci/sci_rpc.h>
 #include "imx8_mu.h"
 
+sc_ipc_t ipc_handle;
+
 DEFINE_BAKERY_LOCK(sc_ipc_bakery_lock);
 #define sc_ipc_lock_init()	bakery_lock_init(&sc_ipc_bakery_lock)
 #define sc_ipc_lock()		bakery_lock_get(&sc_ipc_bakery_lock)