media: lmedm04: use dvb_usbv2_generic_rw_locked

Use dvb-usb-v2 generic usb function for bulk transfers and simplify logic.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>