usb: core: hcd: Create platform devices for onboard hubs in probe()

usb: core: hcd: Create platform devices for onboard hubs in probe()

Call onboard_hub_create/destroy_pdevs() from usb_add/remove_hcd()
for primary HCDs to create/destroy platform devices for onboard
USB hubs that may be connected to the root hub of the controller.
These functions are a NOP unless CONFIG_USB_ONBOARD_HUB=y/m.

Also add a field to struct usb_hcd to keep track of the onboard hub
platform devices that are owned by the HCD.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/20220217104219.v21.3.I7a3a7d9d2126c34079b1cab87aa0b2ec3030f9b7@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>