FROMLIST: usb: core: Prevent null pointer dereference in update_port_device_state

Currently, the function update_port_device_state gets the usb_hub from
udev->parent by calling usb_hub_to_struct_hub.
However, in case the actconfig or the maxchild is 0, the usb_hub would
be NULL and upon further accessing to get port_dev would result in null
pointer dereference.

Fix this by introducing an if check after the usb_hub is populated.

Fixes: 83cb2604 ("usb: core: add sysfs entry for usb device state")
Cc: stable@vger.kernel.org
Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>

Bug: 321600650
Link: https://lore.kernel.org/all/20240110095814.7626-1-quic_ugoswami@quicinc.com/


Change-Id: I3fef553dce36a7ec2d335008fe8d51d848d6abd2
Signed-off-by: Rajashekar kuruva <quic_kuruva@quicinc.com>