change #include "flash.h" to <flash/flash.h>

Changes from the flat namespace to heirarchical one.  Instead of writing:

	#include "flash.h"

the following form should be used.

	#include <flash/flash.h>

The exception is from .c files in the same directory.

src/server/gdb_server.c

@@ -31,7 +31,7 @@
 #include <target/target_request.h>
 #include <target/register.h>
 #include "server.h"
-#include "flash.h"
+#include <flash/flash.h>
 #include "gdb_server.h"
 #include <target/image.h>
 #include <jtag/jtag.h>