xtensa: Use generic asm/mmu.h for nommu

The nommu portion of mmu.h of the extensa platform is basically the same as the
asm-generic mmu.h. So use it instead.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/xtensa/include/asm/mmu.h

@@ -12,7 +12,7 @@
 #define _XTENSA_MMU_H
 
 #ifndef CONFIG_MMU
-#include <asm/nommu.h>
+#include <asm-generic/mmu.h>
 #else
 
 /* Default "unsigned long" context */

arch/xtensa/include/asm/nommu.h

-typedef struct {
-	unsigned long end_brk;
-} mm_context_t;