sh: Fixup __strnlen_user() behaviour.

Drop TIF_USERSPACE and add addr_limit to the thread_info struct.
Subsequently, use that for address checking in strnlen_user() to
ward off bogus -EFAULTs.

Make __strnlen_user() return 0 on exception, rather than -EFAULT.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/processor.h b/include/asm-sh/processor.h
index e99aff7..a227320 100644
--- a/include/asm-sh/processor.h
+++ b/include/asm-sh/processor.h
@@ -149,6 +149,10 @@
 	union sh_fpu_union fpu;
 };
 
+typedef struct {
+	unsigned long seg;
+} mm_segment_t;
+
 /* Count of active tasks with UBC settings */
 extern int ubc_usercnt;