staging: dgap: tty.c: removes smatch warning "ignoring unreachable code"

This patch removes this smatch warning:
info: ignoring unreachable code.

There were instances where there was extra code after
the default action in switch statements. These default
actions ended with a break so the code wasn't being run
at anytime. This patch removes that extra code.

Signed-off-by: Lidza Louina <lidza.louina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>