staging: unisys: visorbus: remove character device interface

Removed the character device interface from visorchipset and
removed the major and minor numbers.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
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>