staging: unisys: visorbus: Remove unnecessary includes for visorchipset.c

Visorchipset.c was including unnecessary include files, either included by
other headers or not needed at all.

Reviewed-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>