feat(mcpwm): support open drain output for generator IO

Closes https://github.com/espressif/esp-idf/issues/11877

components/driver/mcpwm/include/driver/mcpwm_gen.h

@@ -24,6 +24,7 @@ typedef struct {
     struct {
         uint32_t invert_pwm: 1;   /*!< Whether to invert the PWM signal (done by GPIO matrix) */
         uint32_t io_loop_back: 1; /*!< For debug/test, the signal output from the GPIO will be fed to the input path as well */
+        uint32_t io_od_mode: 1;   /*!< Configure the GPIO as open-drain mode */
         uint32_t pull_up: 1;      /*!< Whether to pull up internally */
         uint32_t pull_down: 1;    /*!< Whether to pull down internally */
     } flags;                      /*!< Extra configuration flags for generator */