They were not qdev'ified before. Derive ADBDevice from DeviceState and
convert reset callbacks to DeviceClass::reset, ADBDevice::opaque pointer
to ADBDevice subtypes for mouse and keyboard and adb_{kbd,mouse}_init()
to regular qdev functions.

Fixing Coding Style issues and splitting keyboard and mouse off into
their own files is left for a later point in time.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>