Guitar-Hero comes with a drums extension. Use the newly introduced input
drums-bits to report this back to user-space. This is a usual extension
like any other device. Nothing special to take care of.

We report this to user-space as "Nintendo Wii Remote Drums". There are
other drums (like "RockBand" drums) which we currently do not support and
maybe will at some point. However, it is quite likely that we can report
these via the same interface. This allows user-space to work with them
without knowing the exact branding.
I couldn't find anyone who owns a "RockBand" device, though.
Initial-work-by: Nicolas Adenis-Lamarre <nicolas.adenis.lamarre@gmail.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>