n_gsm: remove unused parameters from gsm_error()

data and flag are unused in gsm_error(), so remove them.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211118071716.11984-1-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>