This commit refactors the USBH and the USB Host Library in the following ways:
- USBH now presents an abstraction of an endpoint (via usbh_ep_handle_t)
- Added separate functions to enqueue/dequeue URBs to a particular endpoint
- USB Host Library no longer calls HCD API directly. Calls USBH endpoint API
instead.
- Renamed "notif_cb" to "proc_req_cb" (Processing Request Callback)
- This is to avoid confusion with FreerTOS task notifications and Host
Library client event notifications.
- The processing functions of each layer (i.e., "xxx_process()") request
calls via the "proc_req_cb"
- The main handling function (i.e., usb_host_lib_handle_events()) is
responsible for calling the required "xxx_process()" of each layer
Following the file renaming to use the "usb_dwc" prefix, this commit
updates the symbol names of those files to use the "usb_dwc" as well.
Some LL functions were also renamed so that the register name is
mentioned.
This commit updates the DWC_OTG based struct/ll/hal file names to
use the prefix "usb_dwc". This naming scheme reduces ambiguity if
another USB controller implementation is added.
As a result, "hcd.c" has been renamed to "hcd_dwc.c"
