media: ddbridge: improve ddb_ports_attach() failure handling

As all error handling improved quite a bit, don't stop attaching frontends
if one of them failed, since - if other tuner modules are connected to
the PCIe bridge - other hardware may just work, so don't break on a single
port failure, but rather initialise as much as possible. Ie. if there are
issues with a C2T2-equipped PCIe bridge card which has additional DuoFlex
modules connected and the bridge generally works, the DuoFlex tuners can
still work fine.

If all ports failed to initialise where connected hardware was detected on
at first, return -ENODEV though to cause this PCI device to fail and free
all allocated resources. In any case, leave a kernel log warning (or
error, even) if things went wrong.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>