isdn: return -EFAULT if copy_from_user() fails

We should be returning -EFAULT here.

Mostly this patch is to silence a smatch warning.  The upper levels
of this driver turn all non-zero return values from isar_load_firmware()
into 1.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hisax/isar.c

@@ -212,9 +212,9 @@ isar_load_firmware(struct IsdnCardState *cs, u_char __user *buf)
 	cs->debug &= ~(L1_DEB_HSCX | L1_DEB_HSCX_FIFO);
 #endif
 	
-	if ((ret = copy_from_user(&size, p, sizeof(int)))) {
+	if (copy_from_user(&size, p, sizeof(int))) {
 		printk(KERN_ERR"isar_load_firmware copy_from_user ret %d\n", ret);
-		return ret;
+		return -EFAULT;
 	}
 	p += sizeof(int);
 	printk(KERN_DEBUG"isar_load_firmware size: %d\n", size);