Extract usb file descriptor of ftdi on Android

Using JNI implementation of QtAndroid, usb file descriptor
of attached ftdi usb device is extracted. This would then
be used for opening usb device on android.
This implementation assumes that permission for usage of
device is already present. This is because of the device_filter
due to which on attaching a recognised usb device (Only ftdi
for now) to android, a dialog pops up asking for permission to
use it with subsurface.
Not an ideal assumption but works sufficiently well.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>