media: usb: siano: Fix general protection fault in smsusb

The syzkaller USB fuzzer found a general-protection-fault bug in the
smsusb part of the Siano DVB driver.  The fault occurs during probe
because the driver assumes without checking that the device has both
IN and OUT endpoints and the IN endpoint is ep1.

By slightly rearranging the driver's initialization code, we can make
the appropriate checks early on and thus avoid the problem.  If the
expected endpoints aren't present, the new code safely returns -ENODEV
from the probe routine.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by:  <syzbot+53f029db71c19a47325a@syzkaller.appspotmail.com>
CC: <stable@vger.kernel.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>