N900 Hardware isp1707
The NXP isp1707 is used as the USB PHY chip. [1].
There is no published datasheet for this chip. It may be available under another name.
It is not connected in a way which the direction of the USB port can be reversed.
This means that host mode is impossible without hardware modifications.
Reportedly connecting pin D3 (ID) to D2 (GND) of the chip will allow direction to be switched. However - this is a challenging rework job, even for those experienced with SMD soldering, and of course will void the warranty!