scsi_ioctl: only warn about unknown opcodes if they are truly unknown.

We could screw up and warn for opcodes that weren't write-safe and the
user tried to use without having write permissions.

Not so bad in itself, but that also destroyed the cmd type information.

Noticed by Michal Schmidt

drivers/block/scsi_ioctl.c

@@ -199,7 +199,7 @@ static int verify_command(struct file *file, unsigned char *cmd)
 			return 0;
 	}
 
-	if (!(type & CMD_WARNED)) {
+	if (!type) {
 		cmd_type[cmd[0]] = CMD_WARNED;
 		printk(KERN_WARNING "scsi: unknown opcode 0x%02x\n", cmd[0]);
 	}