wifi: ray_cs: Utilize strnlen() in parse_addr()

Instead of doing simple operations and using an additional variable on stack,
utilize strnlen() and reuse len variable.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220603164414.48436-1-andriy.shevchenko@linux.intel.com

drivers/net/wireless/ray_cs.c

@@ -1643,31 +1643,29 @@ static void authenticate_timeout(struct timer_list *t)
 /*===========================================================================*/
 static int parse_addr(char *in_str, UCHAR *out)
 {
+	int i, k;
 	int len;
-	int i, j, k;
 	int status;
 
 	if (in_str == NULL)
 		return 0;
-	if ((len = strlen(in_str)) < 2)
+	len = strnlen(in_str, ADDRLEN * 2 + 1) - 1;
+	if (len < 1)
 		return 0;
 	memset(out, 0, ADDRLEN);
 
 	status = 1;
-	j = len - 1;
-	if (j > 12)
-		j = 12;
 	i = 5;
 
-	while (j > 0) {
-		if ((k = hex_to_bin(in_str[j--])) != -1)
+	while (len > 0) {
+		if ((k = hex_to_bin(in_str[len--])) != -1)
 			out[i] = k;
 		else
 			return 0;
 
-		if (j == 0)
+		if (len == 0)
 			break;
-		if ((k = hex_to_bin(in_str[j--])) != -1)
+		if ((k = hex_to_bin(in_str[len--])) != -1)
 			out[i] += k << 4;
 		else
 			return 0;