Split FW download packages smarter way and bug free. Implementation is
based of Andrea Merello's example he provided for tda18218 driver.
Count remaining FW bytes down in loop instead of division and modulo
combination used earlier.

Thanks-to: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Cc: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>