The mouse button emulation calls input device methods from an input
device. This causes funny lock nesting which is harmless as each
device has its own locks.

Give the nesting device its own lock classes so that lockdep will not
consider them the same.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>