kgdb: fix kgdboc dynamic module configuration

Fix the run time configuration of kgdboc such that it does not default
to 9600 baud if you use the "echo" command to configure the sysfs
module paramater.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>