This makes the BL and FW images distinct devices with unique
serial numbers.
Windows (and maybe Mac) remembers the device descriptors and
the associated drivers based on this serial number. Providing
unique serial numbers for the BL and FW images allows us to
provide different sets of descriptors for the BL and FW images
without confusing these OSes.
BL version number is now also bumped to reflect the new
serial number generation algorithm.
Summary of changes:
* USB CDC and HID drivers are completely split apart.
* This will allow different max buffer sizes for HID and CDC.
* USB descriptors have been overhauled:
* Proper structs/macros/enums declared for USB (see pios_usb_defs.h)
* Two common descriptor definitions. One for HID+CDC another for HID only.
See pios_usb_desc_{hid_cdc,hid_only}.c for details.
* Long standing bugs in OP USB descriptors became much more obvious with the
new struct definitions.
* Board specific USB initialization is now in pios_usb_board_data.h in each build target.
* Definition of USB descriptors is now entirely indpendent of STM32 libs.
Glue into STM32 libs is provided by pios_usbhook.c.
* Removed a lot of stale/irrelevant USB #defines throughout the tree.
* Improved naming consistency throughout USB code:
* PIOS_USB_HID_* now refers to the HID endpoint code.
* PIOS_USB_CDC_* now refers to the CDC endpoint code.
* PIOS_USB_* now refers to the low-level USB code.
* PIOS_USB_BOARD_* now refers to board-specific USB data
* PIOS_USBHOOK_* is glue between PIOS and STM32 USB libs.
* struct usb_* and enum usb_* and USB_* and HID_* are all types from the USB spec.
* Shrunk the buffer size on the CDC call mgmt endpoint to save some RAM.
* Made a few more USB related variables static to save some RAM.
