device: add a new macro to obtain the device object symbol name

The new SYS_GET_DEVICE_NAME macro can be used in combination with
SYS_GET_DEVICE to obtain an external reference to a static device
object, e.g.:

extern struct device SYS_GET_DEVICE_NAME(my_device_name);
struct device* dev = SYS_GET_DEVICE(my_device_name);

dev is here set at compile time.

Change-Id: I9094925c685177f01e0cef194ec382ad49658f9d
Signed-off-by: Fabien Chereau <fabien.chereau@intel.com>

include/init.h

@@ -85,6 +85,23 @@
 		 .config = &(config_##name),\
 		 .driver_data = data}
 
+/**
+ * @def SYS_GET_DEVICE_NAME
+ *
+ * @brief Expands to the full name of a global device object
+ *
+ * @details Return the full name of a device object symbol created by
+ * SYS_DEFINE_DEVICE(), using the @name provided to SYS_DEFINE_DEVICE().
+ *
+ * It is meant to be used for declaring extern symbols pointing on device
+ * objects before using the SYS_GET_DEVICE macro to get the device object.
+ *
+ * @param name The same name provided to SYS_DEFINE_DEVICE()
+ *
+ * @return The exanded name of the device object created by SYS_DEFINE_DEVICE()
+ */
+#define SYS_GET_DEVICE_NAME(name) (_CONCAT(__initconfig_, name))
+
 /**
  * @def SYS_GET_DEVICE
  *
@@ -97,6 +114,6 @@
  *
  * @return A pointer to the device object created by SYS_DEFINE_DEVICE()
  */
-#define SYS_GET_DEVICE(name) (&(_CONCAT(__initconfig_, name)))
+#define SYS_GET_DEVICE(name) (&SYS_GET_DEVICE_NAME(name))
 
 #endif /* _INIT_H_ */