[media] gspca: Fix input urb creation / destruction surrounding suspend resume

1) We always re-create the input-urb on resume, so we must also always
   destroy it on suspend to avoid leaking it
2) If we're going to do an init_transfer, then that will destroy the urb
   before starting the stream (nop if there is none), and (re-)create it
   once the stream is started. So there is little use in creating it, if
   we're going to do an init_transfer immediately afterward

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>