configs: pico-imx6ul: convert DM_USB

Here is the test commands:

  => ums 0 mmc 0
  UMS: LUN 0, dev 0, hwpart 0, sector 0x0, count 0x710000
Signed-off-by: NWig Cheng <wig.cheng@technexion.com>
Reviewed-by: NFabio Estevam <festevam@gmail.com>

configs/pico-imx6ul_defconfig

@@ -68,6 +68,7 @@ CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_DM_REGULATOR_GPIO=y
 CONFIG_MXC_UART=y
 CONFIG_USB=y
+CONFIG_DM_USB=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_MANUFACTURER="FSL"
 CONFIG_USB_GADGET_VENDOR_NUM=0x0525