feat(MCPWM): Add mcpwm carrier clk source

The MCPWM carrier is part of the operator and can work independently
without the MCPWM timer being enabled. This commit add the MCPWM
carrier clk source.

components/driver/include/driver/mcpwm_oper.h

@@ -135,6 +135,7 @@ esp_err_t mcpwm_operator_register_event_callbacks(mcpwm_oper_handle_t oper, cons
  * @brief MCPWM carrier configuration structure
  */
 typedef struct {
+    mcpwm_carrier_clock_source_t clk_src;  /*!< MCPWM carrier clock source */
     uint32_t frequency_hz;            /*!< Carrier frequency in Hz */
     uint32_t first_pulse_duration_us; /*!< The duration of the first PWM pulse, in us */
     float duty_cycle;                 /*!< Carrier duty cycle */