Enable EMMC3 Interface On Beagle Board x15

Dear All engineers,

How can I enable MMC3 interface ON AM5728?

Linux Kernerl:Linux arm 4.9.69-ti-rt-r85

I add the following content in the device tree,But MMC3 still fails to mount the device, and need to modify the kernel?

//add the am57xx-beagle-x15-revc.dts
&mmc3 {
  pinctrl-names = "default", "hs", "sdr12", "sdr25", "sdr50";
  pinctrl-0 = <&mmc3_pins_default>;
  pinctrl-1 = <&mmc3_pins_hs>;
  pinctrl-2 = <&mmc3_pins_sdr12>;
  pinctrl-3 = <&mmc3_pins_sdr25>;
  pinctrl-4 = <&mmc3_pins_sdr50>;
    
  max-frequency = <48000000>;
  vmmc-supply = <&vdd_3v3>;
};