drivers: isdn: capi: use simple_strtol to convert numbers

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/capi/capidrv.c

@@ -1515,8 +1515,13 @@ static int decodeFVteln(char *teln, unsigned long *bmaskp, int *activep)
 	while (*s) {
 		int digit1 = 0;
 		int digit2 = 0;
-		if (!isdigit(*s)) return -3;
-		while (isdigit(*s)) { digit1 = digit1*10 + (*s - '0'); s++; }
+		char *endp;
+
+		digit1 = simple_strtoul(s, &endp, 10);
+		if (s == endp)
+			return -3;
+		s = endp;
+
 		if (digit1 <= 0 || digit1 > 30) return -4;
 		if (*s == 0 || *s == ',' || *s == ' ') {
 			bmask |= (1 << digit1);
@@ -1526,8 +1531,12 @@ static int decodeFVteln(char *teln, unsigned long *bmaskp, int *activep)
 		}
 		if (*s != '-') return -5;
 		s++;
-		if (!isdigit(*s)) return -3;
-		while (isdigit(*s)) { digit2 = digit2*10 + (*s - '0'); s++; }
+
+		digit2 = simple_strtoul(s, &endp, 10);
+		if (s == endp)
+			return -3;
+		s = endp;
+
 		if (digit2 <= 0 || digit2 > 30) return -4;
 		if (*s == 0 || *s == ',' || *s == ' ') {
 			if (digit1 > digit2)