stmhal: implement HID OUT endpoint (USB receive)

[prusnak]

This changeset implements HID OUT endpoint, which allows receiving data on the uPy side of things.

Original commits from https://github.com/philandstuff/micropython/tree/usb-hid-out-endpoint, added few more fixes by me.

[prusnak]

Implements #1217

[prusnak]

To test:

• Put this into boot.py:

import pyb
pyb.usb_mode('VCP+HID')

• Run this in uPy REPL:

import pyb
h = pyb.USB_HID()
h.recv(4)

• On PC side do the following:

import hid
h = hid.device()
h.open(0xf055, 0x9801)
h.write([0] + range(4))

recv function should return bytes.

(Also works with packet size of 64, but one needs to specify custom hid descriptor in pyb.usb_mode() function using its hid argument).

[dpgeorge]

The len argument to this function is not used at all, in particular this line could overrun buf if buf is too short.

[dpgeorge]

This is such a simple file. The original copyright is not needed.

[dpgeorge]

Please keep this blank line.

[dpgeorge]

Where did the bulk of this file come from, an ST example?

[prusnak]

Pushed a new commit fixing the issues.

[dpgeorge]

I tested it and there was a bug: needed to adjust size of MAX_TEMPLATE_CONFIG_DESC_SIZE from 100 to 107.

Otherwise it works well. Thanks for the submission, it's a very cool feature to have!

During the merge I squashed some commits in various ways to try and make the history a bit cleaner. See 99d62c4 for last of the 4 commits.

[prusnak]

Thanks!