OHCI: Root hub: Final touches.
Simplify mask size computation.
Remove useless bit_field_size variable in create_hub_descriptor,
value in instance→interrupt_mask_size can be used.
Set interrupt endpoint max packet size to match mask size.
rh_request always returns EOK as errors are indicated via
usb_transfer_batch mechanism, change return type to void.
Get rid of request_without_data function and consolidate request type switch
into one function.
Use new get_feature/set_feature functions to replace the functionality
of removed request_without_data.
Rename:
port_feature_set_request ⇒ set_feature_port
port_feature_clear_request ⇒ clear_feature_port
