Sigmastar infinity6e - #21

Thanks for this, and sorry it has sat for so long. Before we can review it, could you tell us:

• Which board or adapter on sigmastar-infinity6e needs this driver, and what doesn't work without it? The PR has no description.
• Does the in-kernel cdc-acm or ch341 driver handle your chip on this kernel? If so, what does the vendor driver add?

Two things would also need changing if it goes ahead. The branch contains merge commits, and this repo only allows squash and rebase merges, so it would need rebasing. The change also adds trailing spaces to unrelated help text in drivers/usb/serial/Kconfig.

The driver also registers its own tty driver, without using the usb-serial framework, so it may fit better as a firmware package than in this tree.

If we don't hear back, we'll close this PR. You're welcome to reopen it at any time.