mboxd: Refactor and rename mbox.h to mboxd.h

Refine the purpose of the header file to represent what's required for
the daemon itself, not its constituent pieces. Rather, split those
definitions out to their respective header files and include them as
necessary.

Finally the header file is renamed to better reflect its purpose.

Change-Id: I48c409f57d96c844589cd865b24f197477dfe87c
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/flash.h b/flash.h
index f646908..44f5155 100644
--- a/flash.h
+++ b/flash.h
@@ -4,13 +4,15 @@
 #ifndef FLASH_H
 #define FLASH_H
 
+#include <stdint.h>
+
 #define FLASH_DIRTY	0x00
 #define FLASH_ERASED	0x01
 
 /* Estimate as to how long (milliseconds) it takes to access a MB from flash */
 #define FLASH_ACCESS_MS_PER_MB		8000
 
-#include "mbox.h"
+struct mbox_context;
 
 int flash_dev_init(struct mbox_context *context);
 void flash_dev_free(struct mbox_context *context);