Each MCPWM operator has two Trigger (named T0 and T1), and they can be
routed to GPIO fault signal or timer sync event.Generator can be set up
to perform different action on Trigger event.
This commit add a trigger driver and a test for the driver.
set_force_level can only set the generator level before the deadtime module.
if the deadtime module enables the inverter, then the real output level is inverted accordingly
