usb: onboard-hub: Update the bind function based on peer-hub property

usb: onboard-hub: Update the bind function based on peer-hub property

As the "peer-hub" property is optional, don't error out just
skip the bind function.

Fixes: 57e30b09fc ("usb: onboard-hub: Bail out if peer hub is already probed")
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com>