This driver is very big and complex. An error happening in the middle
of any initialization may cause the frontend to not work. So, it
needs to properly propagate error codes internally and to userspace.

Also, printing the error codes at the places it happened helps to
discover were's a bug at the code.

Before this change, a do { } while (0) loop and lots of breaks inside
were used to propagate errors. While this works, if there are
loops inside other loops, it could be easy to forget to add another
break, causing the error to not abort the function.

Also, as not all functions were reporting errors, it is hard to
discover why something failed.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>