staging: unisys: remove visorbus_type extern

The variable visorbus_type could be contained to the visorbus_main.c
file by moving the two functions that referenced it visorchipset.c. This
allowed us to remove the incorrect extern from the include file visorbus.h.

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>