MLK-17108-3 staging: typec: tcpci: don't do force discharge if enable vbus sink

MLK-17108-3 staging: typec: tcpci: don't do force discharge if enable vbus sink

We use vbus force discharge to have a quick vbus off for power role swap,
which works like this: enable vbus force discharge and wait the vbus fall
below vbus low threshold, when reaches, an alarm generated and tcpm can go
forward. but current code do vbus force discharge in any disable source
vbus case, in enable vbus charge case, we firstly disable source vbus and
then turn on vbus sink, in between, vbus force discharge should not be
enabled.

Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Li Jun <jun.li@nxp.com>