redfin: usb: add state of usb extcon to monitorffs

Monitorffs needs to check the state of usb extcon to pull up
USB gadget. Therefore, this patch add state of usb extcon and
send this information to monitorffs.

Bug: 173086594
Test: verified pass
Merged-In: I29df29efcf55118241f0ca7072b034c1fb5a37f2
Change-Id: I2c19f769991b014dfa7051e114abfecc40b90a6e
1 file changed