usb-console: pass baud from console to the initial tty open

The usb console code has had a long standing problem of not being able
to pass the baud rate from the kernel argument console=ttyUSB0,BAUD
down to the initial tty open, unless you were willing to settle for
9600 baud.

The solution is to directly use tty_init_termios() in
usb_console_setup() as this will preserve any changes to the initial
termios setting on future opens.

CC: Alan Cox <alan@linux.intel.com>
CC: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>