isdn/gigaset: improve bas_gigaset USB error reporting

Rephrase some USB error messages to make them clearer and more consistent.
Downgrade some warning messages that may occur during normal operation to
debug messages.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed