USB: serial: do not forward USB specific errors in open

Use usb_translate_errors() to map USB-specific errors to errors
appropriate for user space (ENOMEM, ENODEV and EIO) in open.

Currently almost all serial drivers simply forward error codes from the
stack (e.g. from usb_submit_urb()), but these codes often have
different meanings in user-space. Doing the mapping in usb-serial core
simplifies driver code and allows for more consistent error reporting.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>