openrisc: use generic strncpy_from_user

As per commits 2922585b9329 ("lib: Sparc's strncpy_from_user is generic
enough, move under lib/") and 92ae03f2ef99 ("x86: merge 32/64-bit
versions of 'strncpy_from_user()' and speed it up"), and corresponding
discussion on linux-arch.

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/openrisc/include/asm/uaccess.h b/arch/openrisc/include/asm/uaccess.h
index f5abaa0..04b93de 100644
--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -313,14 +313,10 @@
 	return size;
 }
 
-extern int __strncpy_from_user(char *dst, const char *src, long count);
+#define user_addr_max() \
+	(segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 
-static inline long strncpy_from_user(char *dst, const char *src, long count)
-{
-	if (access_ok(VERIFY_READ, src, 1))
-		return __strncpy_from_user(dst, src, count);
-	return -EFAULT;
-}
+extern long strncpy_from_user(char *dest, const char __user *src, long count);
 
 /*
  * Return the size of a string (including the ending 0)