drivers/input: Fix warnings and enable Werror

Correct signedness for comparisons, remove unused code, remove unused variable, correct variable type for callbacks

Part of #9460

Change-Id: Ie48e8498e0830ed8b175986aaf82b94a1d99b72f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4570
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Updated HID code with Vector class instead of hand made growing arrays

Change-Id: Iec8cd3922d9c21a046d225181d326253ae88d395
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4324
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: John Scipione <jscipione@gmail.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

i2c_hid: driver for i2c-hid devices

This is getting more common in tablets and laptops. It replaces PS/2 for
the internal keyboard and pointing devices. This is simpler and cheaper
than using up USB ports, and also simpler than the old and quirky PS/2
protocol.

The HID spec is the same no matter what transport is used (it is also
applicable for Bluetooth). Ideally we could create a separate HID bus
manager that would handle all these devices in a generic way, but that
is a lot of work nad extra complications for uncertain gains.

For now, just move the common files to a shared directory where both
drivers can use them. As a result the files are compiled twice, which is
what we want, because currently they hardcode some device paths that
need to be different for each driver.

Change-Id: I0327f6864dd0a4372b708f7b7ecf299aa86a6ea9
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2466
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>