[S390] cio: remove custom implementation of hex_to_bin()

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/blacklist.c

@@ -79,17 +79,15 @@ static int pure_hex(char **cp, unsigned int *val, int min_digit,
 		    int max_digit, int max_val)
 {
 	int diff;
-	unsigned int value;
 
 	diff = 0;
 	*val = 0;
 
-	while (isxdigit(**cp) && (diff <= max_digit)) {
+	while (diff <= max_digit) {
+		int value = hex_to_bin(**cp);
 
-		if (isdigit(**cp))
-			value = **cp - '0';
-		else
-			value = tolower(**cp) - 'a' + 10;
+		if (value < 0)
+			break;
 		*val = *val * 16 + value;
 		(*cp)++;
 		diff++;