V4L/DVB (5234): Gl861: remove unneeded declaration

remove unneeded declaration of .generic_bulk_ctrl_endpoint

generic_bulk_ctrl_endpoint isn't being used in this device, so this
is not needed here.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>