USB: dbgp: insert cr prior to nl as needed

The rs232 drivers send a carriage return prior to a new line in the
early printk code.

The usb debug driver should do the same because you want to be able to
use the same terminal programs and tools for analysis of early printk
data.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>