[Blackfin] arch: Initial checkin of the memory protection support.

Enable it with CONFIG_MPU.

Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/include/asm-blackfin/mmu.h b/include/asm-blackfin/mmu.h
index 11d52f1..757e439 100644
--- a/include/asm-blackfin/mmu.h
+++ b/include/asm-blackfin/mmu.h
@@ -24,7 +24,9 @@
 	unsigned long	exec_fdpic_loadmap;
 	unsigned long	interp_fdpic_loadmap;
 #endif
-
+#ifdef CONFIG_MPU
+	unsigned long *page_rwx_mask;
+#endif
 } mm_context_t;
 
 #endif