greybus: uart-gb: clean up send_line_coding

We always pass the same option to send_line_coding() for the line_coding
structure, which is already in the struct gb_tty variable, so just
remove the second parameter as it's not needed.

This logic came from the cdc-acm.c driver, where it's also not needed
anymore, I'll go fix up that later on when I get a chance.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>