[media] mceusb: improve error logging

A number of recent bug reports involve usb_submit_urb() failing which was
only reported with debug parameter on. In addition, remove custom debug
function.

[m.chehab@samsung.com: patch rebased, as one of the patches on this
 series need changes]
Signed-off-by: Sean Young <sean@mess.org>

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>