usb: mtu3: fix an unrecognized issue when connected with PC

When boot on the platform with the USB cable connected to Win7,
the Win7 will pop up an error dialog: "USB Device not recognized",
but finally the Win7 can enumerate it successfully.
The root cause is as the following:
When the xHCI driver set PORT_POWER of the OTG port, and if both
IDPIN and VBUS_VALID are high at the same time, the MTU3 controller
will set SESSION and pull up DP, so the Win7 can detect existence
of USB device, but if the mtu3 driver can't switch to device mode
during the debounce time, the Win7 can not enumerate it.
Here to fix it by removing the 1s delayed EXTCON register to speed up
mode switch.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>