drivers: visorbus: move driver out of staging

Move the visorbus driver out of staging (drivers/staging/unisys/visorbus)
and to drivers/visorbus. Modify the configuration and makefiles so they
now reference the new location. The s-Par header file visorbus.h that is
referenced by all s-Par drivers, is being moved into include/linux.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>