Bluetooth: remove unused bt-nokia-h4p.h header

Nothing in tree use this header which seems a remains of a staging
driver.
This patch remove it.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>