staging: unisys: visorbus: Remove notifier-related code from visorbus

When this functionality was first implemented, visorchipset and visorbus
were separate drivers, which necessitated a registration mechanism for
them to communicate.  More-recently, visorchipset and visorbus were
combined into a single driver, and now exist as separate source files
within the same driver, known as 'visorbus'.  This eliminated the need
for a registration mechanism, but it has remained nevertheless until now.
For the sake of simplification, this registration mechanism is now being
removed.

Signed-off-by: David Binder <david.binder@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Acked-By: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>