USB-serial update for 6.15-rc1

Here's a single USB-serial cleanup for 6.15-rc1 that's been sitting in
linux-next for a few weeks without any reported issues.

USB: serial: mos7840: drop unused defines

Drop some defines that have never (really) been used, some of which are
duplicates (the read and write requests) and others which are just bogus
(the ioctl).

Signed-off-by: Johan Hovold <johan@kernel.org>