Input: ims-pcu - validate number of endpoints before using them

Input: ims-pcu - validate number of endpoints before using them

BugLink: http://bugs.launchpad.net/bugs/1677589
commit 1916d319271664241b7aa0cd2b05e32bdb310ce9 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer should a malicious device lack control-interface endpoints.

Fixes: 628329d52474 ("Input: add IMS Passenger Control Unit driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>