Fix .write_endpoint values for HIDs without an OUT endpoint

Proposed changes

In these cases the writes correctly go through the control/default/zero endpoint. However, the .write_endpoint field for these devices was incorrectly computed and the resulting endpoint address was invalid (e.g. bit 5, set by LIBUSB_REQUEST_TYPE_CLASS, is reserved in endpoint addresses).

In fact, neither LIBUSB_REQUEST_TYPE_CLASS nor LIBUSB_RECIPIENT_INTERFACE had a place in this definition: these flags should only be used to build bmRequestType parameters for control transfers.

The issue was only harmless because .write_endpoint is not used in corsairlink_coolit_write. This patch avoids future confusion about this.¹

¹ Related: #214

Types of changes

[x] Bugfix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

[x] I have read the CONTRIBUTING doc
[x] Make sure you are requesting to pull a topic/feature/bugfix branch (right side). Don't request your master!
[x] Make sure you are making a pull request against the testing branch (left side). Also you should start your branch off our testing.
[ ] Lint and unit tests pass locally with my changes
[ ] I have added tests that prove my fix is effective or that my feature works
[x] I have added necessary documentation (if appropriate)
[x] Any dependent changes have been merged and published in downstream modules
[x] Check the commit's or even all commits' message styles matches our requested structure.

audiohacked / OpenCorsairLink