Input: gtco - fix crash on detecting device without endpoints

commit 162f98dea487206d9ab79fc12ed64700667a894d upstream.

The gtco driver expects at least one valid endpoint. If given malicious
descriptors that specify 0 for the number of endpoints, it will crash in
the probe function. Ensure there is at least one endpoint on the interface
before using it.

Also let's fix a minor coding style issue.

The full correct report of this issue can be found in the public
Red Hat Bugzilla:

https://bugzilla.redhat.com/show_bug.cgi?id=1283385



Change-Id: I35712c4372444e262ceb02f09b69480cd9155566
Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>