mcpwm_generator_set_dead_time() function

- ESP_OK: Set dead time for MCPWM generator successfully - ESP_ERR_INVALID_ARG: Set dead time for MCPWM generator failed because of invalid argument - ESP_ERR_INVALID_STATE: Set dead time for MCPWM generator failed because of invalid state (e.g. delay module is already in use by other generator) - ESP_FAIL: Set dead time for MCPWM generator failed because of other error

Due to a hardware limitation, you can't set rising edge delay for both MCPWM generator 0 and 1 at the same time, otherwise, there will be a conflict inside the dead time module. The same goes for the falling edge setting. But you can set both the rising edge and falling edge delay for the same MCPWM generator.