ubifs: Make r5 hash binary string aware

As of now all filenames known by UBIFS are strings with a NUL
terminator. With encrypted filenames a filename can be any binary
string and the r5 function cannot search for the NUL terminator.
UBIFS always knows how long a filename is, therefore we can change
the hash function to iterate over the filename length to work
correctly with binary strings.
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/key.h

@@ -69,7 +69,7 @@ static inline uint32_t key_r5_hash(const char *s, int len)
 	uint32_t a = 0;
 	const signed char *str = (const signed char *)s;
 
-	while (*str) {
+	while (len--) {
 		a += *str << 4;
 		a += *str >> 4;
 		a *= 11;