Staging: remove wusbcore and UWB from the kernel tree.

It's been over 6 months, and no one has noticed that these drivers are
deleted, probably because no one actually has this hardware.  As no one
has volunteered to maintain the code, let's drop it for good.

Link: https://lore.kernel.org/r/20200210231417.GA1736729@kroah.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>