When the bandwidth is not wide enough, the transfer endpoint may be set to
the one of the alternate setting 0. This one may be null and this causes a
divide by 0 oops.
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>