Blackfin: Annotate strncpy_from_user src parameter with __user

The src parameter of strncpy_from_user is supposed to take a string from
userspace, so it should be annotated with __user. Doing so fixes the following
and similar warnings from sparse:

	kernel/sys.c:491:51: warning: incorrect type in argument 2 (different address spaces)
	kernel/sys.c:491:51:    expected char const *src
	kernel/sys.c:491:51:    got void [noderef] <asn:1>*arg
	kernel/sys.c:2061:54: warning: incorrect type in argument 2 (different address spaces)
	kernel/sys.c:2061:54:    expected char const *src
	kernel/sys.c:2061:54:    got char [noderef] <asn:1>*<noident>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Bob Liu <lliubbo@gmail.com>

arch/blackfin/include/asm/uaccess.h

@@ -216,12 +216,12 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
  */
 
 static inline long __must_check
-strncpy_from_user(char *dst, const char *src, long count)
+strncpy_from_user(char *dst, const char __user *src, long count)
 {
 	char *tmp;
 	if (!access_ok(VERIFY_READ, src, 1))
 		return -EFAULT;
-	strncpy(dst, src, count);
+	strncpy(dst, (const char __force *)src, count);
 	for (tmp = dst; *tmp && count > 0; tmp++, count--) ;
 	return (tmp - dst);
 }