UPSTREAM: Input: powermate - fix oops with malicious USB descriptors

The powermate driver expects at least one valid USB endpoint in its
probe function.  If given malicious descriptors that specify 0 for
the number of endpoints, it will crash.  Validate the number of
endpoints on the interface before using them.

The full report for this issue can be found here:
http://seclists.org/bugtraq/2016/Mar/85



BUG: 28242610

Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Change-Id: I1cb956a35f3bba73324240d5bd0a029f49d3c456