staging: remove nokia_hp4p driver

The Bluetooth maintainer has been complaining about it for a while, and
I shouldn't have merged it over his objections.  There also has been no
real work done on it at all to get it out of the staging tree, so just
delete the code for now.

If someone wants to get this fixed up properly, feel free to revert this
commit and send the revert, along with cleanups and we will be glad to
consider it.

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>,
Cc: Miguel Oliveira <cmroliv@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>