gpio: mpsse: support bryx radio interface kit

gpio: mpsse: support bryx radio interface kit

This device is powered by an FT232H, which is very similar to the
FT2232H this driver was written for. The key difference is it has only
one MPSSE instead of two. As a result, it presents only one USB
interface to the system, which conveniently "just works" out of the box
with this driver.

The brik exposes only two GPIO lines which are hardware limited to only
be useful in one direction. As a result, I've restricted things on the
driver side to refuse to configure any other lines.

This device, unlike the sealevel device I wrote this driver for
originally, is hotpluggable, which makes for all sorts of weird
edgecases. I've tried my best to stress-test the parts that could go
wrong, but given the new usecase, more heads taking a critical look at
the teardown and synchronization bits on the driver as a whole would be
appreciated.

Signed-off-by: Mary Strodl <mstrodl@csh.rit.edu>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20251014133530.3592716-5-mstrodl@csh.rit.edu
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>