iosys-map: Add IOSYS_MAP_INIT_VADDR_IOMEM()

Add IOSYS_MAP_INIT_VADDR_IOMEM() for static init of variables of type
struct iosys_map.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Lucas De Marchi <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

include/linux/iosys-map.h

···
  *
  *	iosys_map_set_vaddr(&map, 0xdeadbeaf);
  *
- * To set an address in I/O memory, use iosys_map_set_vaddr_iomem().
+ * To set an address in I/O memory, use IOSYS_MAP_INIT_VADDR_IOMEM() or
+ * iosys_map_set_vaddr_iomem().
  *
  * .. code-block:: c
+ *
+ *	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(0xdeadbeaf);
  *
  *	iosys_map_set_vaddr_iomem(&map, 0xdeadbeaf);
  *
···
 	{				\
 		.vaddr = (vaddr_),	\
 		.is_iomem = false,	\
+	}
+
+/**
+ * IOSYS_MAP_INIT_VADDR_IOMEM - Initializes struct iosys_map to an address in I/O memory
+ * @vaddr_iomem_:	An I/O-memory address
+ */
+#define IOSYS_MAP_INIT_VADDR_IOMEM(vaddr_iomem_)	\
+	{						\
+		.vaddr_iomem = (vaddr_iomem_),		\
+		.is_iomem = true,			\
 	}
 
 /**