Instead of defining its own set of error codes, use the linux
native ones.

Please note that this patch made a "stupid" error code mapping, just
replacing the codes with the closest one. In special, -EIO is being
used on several places. I'm pretty sure this could be better assigned,
but a change like that would require lots o time and efforts, without
much benefit.

So lets do adjstments at the error codes latter, when we have more
time.
Acked-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>