USB: serial: safe-serial: fix up printk() usage

The driver was calling printk() directly at startup, which is just
noise.  Switch over to using pr_info() where needed, and get rid of the
totally useless version number that had never ever been incremented.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>